TanStack SPA migration to TanStack Start SSR

Hey guys, we've rewritten our project from SPA React to SSR using TanStack Start, but we're running into a problem where the loader methods of the routes are executed correctly in the local dev environment, but on the cloud instance on our server (Docker), the loader methods are executed, but the result of the API calls is always empty.

Does anyone have any idea how we can solve this problem?