Create following page in routes

<!-- src/routes/[slug].svelte -->
<script>
  import { page } from '$app/stores';
  let p_slug = $page.params.slug;
</script>

<h1>{p_slug}</h1>
<a href={`${p_slug}_x`}>Click me - {p_slug}</a>

In production build or in dev build without code edits p_slug is constant since I visit any page like http://localhost:3000/test

Even if I click on link "Click me - test", p_slug will not change.

This is good expected behaviour.

Now the issue.

In dev mode visit http://localhost:3000/test then click on "Click me - test" link (url will be changed to /test_x)

Edit src/routes/[slug].svelte like add something to h1.

Visit page again at http://localhost:3000/test

Click on link and see that p_slug is equal to test_x what is different behaviour from above.