fromStore() in combination with $derived seems broken

[brunnerh]

Describe the bug

$derived values based on an object created by fromStore() do not seem to update.

Found by @dusty-phillips (see #13998).

Reproduction

class ThemeState {
  #storeState = fromStore(store)
  value = $derived(this.#storeState.current) // does not update
}

Full reproduction playground

I tried using $derived.by and a plain JS object instead of a class, neither change seemed to have any effect.

Sync via $effect works.

Logs

No response

System Info

REPL

Severity

annoyance

[trueadm]

A more interesting case is this: https://svelte.dev/playground/dc5073f43caa4def903817a94a1e32b5?version=5.1.3