HMR doesn't work for server data changes

[enyo]

Describe the bug

When making changes to server data (the data returned from the load function in +page.server.ts) HMR doesn't work: changes aren't reflected on the client (the client does not fetch the data object again).

Reproduction URL

https://www.sveltelab.dev/wftni3wiwdywe1a

Reproduction

Create a default SvelteKit project, upgrade all dependencies to their latest version, and make changes to a +page.server.ts file.

System Info

"@sveltejs/vite-plugin-svelte": "^5.0.0",
"vite": "^6.0.0"

The problem does not happen with vite-plugin-svelte ^4.0.0 and vite ^5.0.0.

[dominikg]

moved to sveltekit repo as vite-plugin-svelte does not handle +page.server.ts files