journalctl /usr/bin/plasmashell -f
if you get empty, try command belowplasmashell --replace
You need to re-login to run plasmashell normally after this command.
Please choose the log after you open the wallpaper plugin setting.
build standalone viewer with -DCMAKE_BUILD_TYPE=Debug
install vulkan-validation-layers
run ./sceneviewer --valid-layer <steamapps>/common/wallpaper_engine/assets <steamapps>/workshop/content/431960/<workshop_id>/scene.pkg