diff --git a/internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/OpenPlayer.java b/internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/OpenPlayer.java
index 347d9cb9..34c0891f 100644
--- a/internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/OpenPlayer.java
+++ b/internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/OpenPlayer.java
@@ -19,7 +19,6 @@
 import net.minecraft.Util;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtIo;
-import net.minecraft.nbt.NbtUtils;
 import net.minecraft.nbt.NumericTag;
 import net.minecraft.nbt.Tag;
 import net.minecraft.server.level.ServerPlayer;
@@ -27,13 +26,48 @@
 import org.apache.logging.log4j.LogManager;
 import org.bukkit.craftbukkit.v1_19_R3.CraftServer;
 import org.bukkit.craftbukkit.v1_19_R3.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
+import java.util.Set;
 
 public class OpenPlayer extends CraftPlayer {
 
+    private static final Set<String> RESET_TAGS = Set.of(
+        // net.minecraft.world.Entity#saveWithoutId(CompoundTag)
+        "CustomName",
+        "CustomNameVisible",
+        "Silent",
+        "NoGravity",
+        "Glowing",
+        "TicksFrozen",
+        "HasVisualFire",
+        "Tags",
+        "Passengers",
+        // net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
+        // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+        "warden_spawn_tracker",
+        "enteredNetherPosition",
+        "SpawnX",
+        "SpawnY",
+        "SpawnZ",
+        "SpawnForced",
+        "SpawnAngle",
+        "SpawnDimension",
+        // net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
+        "ShoulderEntityLeft",
+        "ShoulderEntityRight",
+        "LastDeathLocation",
+        // net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
+        "ActiveEffects",
+        "SleepingX",
+        "SleepingY",
+        "SleepingZ",
+        "Brain"
+    );
+
     public OpenPlayer(CraftServer server, ServerPlayer entity) {
         super(server, entity);
     }
@@ -56,12 +90,13 @@ public void saveData() {
         try {
             PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
 
-            CompoundTag playerData = player.saveWithoutId(new CompoundTag());
+            CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player);
+            CompoundTag playerData = getWritableTag(oldData);
+            playerData = player.saveWithoutId(playerData);
             setExtraData(playerData);
 
-            if (!isOnline()) {
-                // Preserve certain data when offline.
-                CompoundTag oldData = worldNBTStorage.load(player);
+            if (oldData != null) {
+                // Revert certain special data values when offline.
                 revertSpecialValues(playerData, oldData);
             }
 
@@ -75,27 +110,22 @@ public void saveData() {
         }
     }
 
-    private void revertSpecialValues(@NotNull CompoundTag newData, @Nullable CompoundTag oldData) {
+    @Contract("null -> new")
+    private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
         if (oldData == null) {
-            return;
+            return new CompoundTag();
         }
 
-        // Prevent vehicle deletion.
-        if (oldData.contains("RootVehicle", Tag.TAG_COMPOUND)) {
-            // See net.minecraft.server.players.PlayerList#save(ServerPlayer)
-            // See net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
-            try {
-                Tag attach = oldData.get("Attach");
-                if (attach != null) {
-                    newData.putUUID("Attach", NbtUtils.loadUUID(attach));
-                }
-            } catch (IllegalArgumentException ignored) {
-                // Likely will not re-mount successfully, but at least the mount will not be deleted.
-            }
-            newData.put("Entity", oldData.getCompound("Entity"));
-            newData.put("RootVehicle", oldData.getCompound("RootVehicle"));
-        }
+        // Copy old data. This is a deep clone, so operating on it should be safe.
+        oldData = oldData.copy();
+
+        // Remove vanilla/server data that is not written every time.
+        oldData.getAllKeys().removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
 
+        return oldData;
+    }
+
+    private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
         // Revert automatic updates to play timestamps.
         copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
         copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
@@ -111,8 +141,8 @@ private <T extends Tag> void copyValue(
         CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
         CompoundTag newContainer = getTag(target, container, CompoundTag.class);
 
-        // Container being null means the server implementation doesn't store this data.
-        if (oldContainer == null || newContainer == null) {
+        // New container being null means the server implementation doesn't store this data.
+        if (newContainer == null) {
             return;
         }
 
@@ -121,9 +151,12 @@ private <T extends Tag> void copyValue(
     }
 
     private <T extends Tag> @Nullable T getTag(
-        @NotNull CompoundTag container,
+        @Nullable CompoundTag container,
         @NotNull String key,
         @NotNull Class<T> dataType) {
+        if (container == null) {
+            return null;
+        }
         Tag value = container.get(key);
         if (value == null || !dataType.isAssignableFrom(value.getClass())) {
             return null;
diff --git a/internal/v1_20_R2/src/main/java/com/lishid/openinv/internal/v1_20_R2/OpenPlayer.java b/internal/v1_20_R2/src/main/java/com/lishid/openinv/internal/v1_20_R2/OpenPlayer.java
index 4388d823..33677e0d 100644
--- a/internal/v1_20_R2/src/main/java/com/lishid/openinv/internal/v1_20_R2/OpenPlayer.java
+++ b/internal/v1_20_R2/src/main/java/com/lishid/openinv/internal/v1_20_R2/OpenPlayer.java
@@ -20,20 +20,55 @@
 import net.minecraft.Util;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtIo;
-import net.minecraft.nbt.NbtUtils;
 import net.minecraft.nbt.NumericTag;
 import net.minecraft.nbt.Tag;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.level.storage.PlayerDataStorage;
 import org.bukkit.craftbukkit.v1_20_R2.CraftServer;
 import org.bukkit.craftbukkit.v1_20_R2.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
+import java.util.Set;
 
 public class OpenPlayer extends CraftPlayer {
 
+    private static final Set<String> RESET_TAGS = Set.of(
+        // net.minecraft.world.Entity#saveWithoutId(CompoundTag)
+        "CustomName",
+        "CustomNameVisible",
+        "Silent",
+        "NoGravity",
+        "Glowing",
+        "TicksFrozen",
+        "HasVisualFire",
+        "Tags",
+        "Passengers",
+        // net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
+        // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+        "warden_spawn_tracker",
+        "enteredNetherPosition",
+        "SpawnX",
+        "SpawnY",
+        "SpawnZ",
+        "SpawnForced",
+        "SpawnAngle",
+        "SpawnDimension",
+        // net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
+        "ShoulderEntityLeft",
+        "ShoulderEntityRight",
+        "LastDeathLocation",
+        // net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
+        "ActiveEffects", // Backwards compat: Renamed from 1.19
+        "active_effects",
+        "SleepingX",
+        "SleepingY",
+        "SleepingZ",
+        "Brain"
+    );
+
     public OpenPlayer(CraftServer server, ServerPlayer entity) {
         super(server, entity);
     }
@@ -50,12 +85,13 @@ public void saveData() {
         try {
             PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
 
-            CompoundTag playerData = player.saveWithoutId(new CompoundTag());
+            CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player);
+            CompoundTag playerData = getWritableTag(oldData);
+            playerData = player.saveWithoutId(playerData);
             setExtraData(playerData);
 
-            if (!isOnline()) {
-                // Preserve certain data when offline.
-                CompoundTag oldData = worldNBTStorage.load(player);
+            if (oldData != null) {
+                // Revert certain special data values when offline.
                 revertSpecialValues(playerData, oldData);
             }
 
@@ -69,27 +105,22 @@ public void saveData() {
         }
     }
 
-    private void revertSpecialValues(@NotNull CompoundTag newData, @Nullable CompoundTag oldData) {
+    @Contract("null -> new")
+    private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
         if (oldData == null) {
-            return;
+            return new CompoundTag();
         }
 
-        // Prevent vehicle deletion.
-        if (oldData.contains("RootVehicle", Tag.TAG_COMPOUND)) {
-            // See net.minecraft.server.players.PlayerList#save(ServerPlayer)
-            // See net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
-            try {
-                Tag attach = oldData.get("Attach");
-                if (attach != null) {
-                    newData.putUUID("Attach", NbtUtils.loadUUID(attach));
-                }
-            } catch (IllegalArgumentException ignored) {
-                // Likely will not re-mount successfully, but at least the mount will not be deleted.
-            }
-            newData.put("Entity", oldData.getCompound("Entity"));
-            newData.put("RootVehicle", oldData.getCompound("RootVehicle"));
-        }
+        // Copy old data. This is a deep clone, so operating on it should be safe.
+        oldData = oldData.copy();
+
+        // Remove vanilla/server data that is not written every time.
+        oldData.getAllKeys().removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
 
+        return oldData;
+    }
+
+    private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
         // Revert automatic updates to play timestamps.
         copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
         copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
@@ -105,8 +136,8 @@ private <T extends Tag> void copyValue(
         CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
         CompoundTag newContainer = getTag(target, container, CompoundTag.class);
 
-        // Container being null means the server implementation doesn't store this data.
-        if (oldContainer == null || newContainer == null) {
+        // New container being null means the server implementation doesn't store this data.
+        if (newContainer == null) {
             return;
         }
 
@@ -115,9 +146,12 @@ private <T extends Tag> void copyValue(
     }
 
     private <T extends Tag> @Nullable T getTag(
-        @NotNull CompoundTag container,
+        @Nullable CompoundTag container,
         @NotNull String key,
         @NotNull Class<T> dataType) {
+        if (container == null) {
+            return null;
+        }
         Tag value = container.get(key);
         if (value == null || !dataType.isAssignableFrom(value.getClass())) {
             return null;
diff --git a/internal/v1_20_R3/src/main/java/com/lishid/openinv/internal/v1_20_R3/OpenPlayer.java b/internal/v1_20_R3/src/main/java/com/lishid/openinv/internal/v1_20_R3/OpenPlayer.java
index 23ed6bb9..08017f9f 100644
--- a/internal/v1_20_R3/src/main/java/com/lishid/openinv/internal/v1_20_R3/OpenPlayer.java
+++ b/internal/v1_20_R3/src/main/java/com/lishid/openinv/internal/v1_20_R3/OpenPlayer.java
@@ -20,21 +20,56 @@
 import net.minecraft.Util;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtIo;
-import net.minecraft.nbt.NbtUtils;
 import net.minecraft.nbt.NumericTag;
 import net.minecraft.nbt.Tag;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.level.storage.PlayerDataStorage;
 import org.bukkit.craftbukkit.v1_20_R3.CraftServer;
 import org.bukkit.craftbukkit.v1_20_R3.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Set;
 
 public class OpenPlayer extends CraftPlayer {
 
+    private static final Set<String> RESET_TAGS = Set.of(
+        // net.minecraft.world.Entity#saveWithoutId(CompoundTag)
+        "CustomName",
+        "CustomNameVisible",
+        "Silent",
+        "NoGravity",
+        "Glowing",
+        "TicksFrozen",
+        "HasVisualFire",
+        "Tags",
+        "Passengers",
+        // net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
+        // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+        "warden_spawn_tracker",
+        "enteredNetherPosition",
+        "SpawnX",
+        "SpawnY",
+        "SpawnZ",
+        "SpawnForced",
+        "SpawnAngle",
+        "SpawnDimension",
+        // net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
+        "ShoulderEntityLeft",
+        "ShoulderEntityRight",
+        "LastDeathLocation",
+        // net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
+        "ActiveEffects", // Backwards compat: Renamed from 1.19
+        "active_effects",
+        "SleepingX",
+        "SleepingY",
+        "SleepingZ",
+        "Brain"
+    );
+
     public OpenPlayer(CraftServer server, ServerPlayer entity) {
         super(server, entity);
     }
@@ -51,12 +86,13 @@ public void saveData() {
         try {
             PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
 
-            CompoundTag playerData = player.saveWithoutId(new CompoundTag());
+            CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player);
+            CompoundTag playerData = getWritableTag(oldData);
+            playerData = player.saveWithoutId(playerData);
             setExtraData(playerData);
 
-            if (!isOnline()) {
-                // Preserve certain data when offline.
-                CompoundTag oldData = worldNBTStorage.load(player);
+            if (oldData != null) {
+                // Revert certain special data values when offline.
                 revertSpecialValues(playerData, oldData);
             }
 
@@ -71,27 +107,23 @@ public void saveData() {
         }
     }
 
-    private void revertSpecialValues(@NotNull CompoundTag newData, @Nullable CompoundTag oldData) {
+    @Contract("null -> new")
+    private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
         if (oldData == null) {
-            return;
+            return new CompoundTag();
         }
 
-        // Prevent vehicle deletion.
-        if (oldData.contains("RootVehicle", Tag.TAG_COMPOUND)) {
-            // See net.minecraft.server.players.PlayerList#save(ServerPlayer)
-            // See net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
-            try {
-                Tag attach = oldData.get("Attach");
-                if (attach != null) {
-                    newData.putUUID("Attach", NbtUtils.loadUUID(attach));
-                }
-            } catch (IllegalArgumentException ignored) {
-                // Likely will not re-mount successfully, but at least the mount will not be deleted.
-            }
-            newData.put("Entity", oldData.getCompound("Entity"));
-            newData.put("RootVehicle", oldData.getCompound("RootVehicle"));
-        }
+        // Copy old data. This is a deep clone, so operating on it should be safe.
+        oldData = oldData.copy();
+
+        // Remove vanilla/server data that is not written every time.
+        oldData.getAllKeys()
+            .removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
 
+        return oldData;
+    }
+
+    private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
         // Revert automatic updates to play timestamps.
         copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
         copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
@@ -107,8 +139,8 @@ private <T extends Tag> void copyValue(
         CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
         CompoundTag newContainer = getTag(target, container, CompoundTag.class);
 
-        // Container being null means the server implementation doesn't store this data.
-        if (oldContainer == null || newContainer == null) {
+        // New container being null means the server implementation doesn't store this data.
+        if (newContainer == null) {
             return;
         }
 
@@ -117,9 +149,12 @@ private <T extends Tag> void copyValue(
     }
 
     private <T extends Tag> @Nullable T getTag(
-        @NotNull CompoundTag container,
+        @Nullable CompoundTag container,
         @NotNull String key,
         @NotNull Class<T> dataType) {
+        if (container == null) {
+            return null;
+        }
         Tag value = container.get(key);
         if (value == null || !dataType.isAssignableFrom(value.getClass())) {
             return null;