[svelte] Why can't I bind to a `createQuery` result?

Describe the bug

Using Svelte (v5.42.3) and Svelte Kit (v2.48.2) and @tanstack/svelte-query (v6.0.3).

If I have the component Player.svelte:

<script lang="ts">
    import { createQuery } from '@tanstack/svelte-query';

    const playerStore = createQuery(() => ({
        queryKey: "key",
        queryFn: playerById(page.params.player_id),
    }));

    let { data: player } = $derived(playerStore);
</script>

<FormPlayers bind:player={player} />

and FormPlayers.svelte:

<script lang="ts">
    type Props = {
        player: Player;
    };

    let {
        player = $bindable(),
    }: Props = $props();
</script>

{#each player.skills as skill, index (skill.id)}
    <FormPlayerSkill bind:skill={player.skills[index]} />
{/each}

and FormPlayerSkill.svelte:

<script lang="ts">
    type Props = {
        skill: PlayerSkillInput;
    };

    let {
        skill = $bindable()
    }: Props = $props();
</script>

<Date bind:date={skill.date} />

I get the error:

FormPlayers.svelte:77 [svelte] binding_property_non_reactive
`bind:skill={player.skills[index]}` (src/routes/players/FormPlayers.svelte:40:4) is binding to a non-reactive property
https://svelte.dev/e/binding_property_non_reactive

Why? Isn't the let { data: player } = $derived(playerStore) assignable / bindable / editable / "Sveltable"?

Your minimal, reproducible example

I'll post ASAP (it's not easy).

Tanstack Query adapter

svelte-query

TanStack Query version

6.0.3

TypeScript version

5.9.3

Start with the linked Svelte playground and reproduce the warning using the Player.svelte, FormPlayers.svelte, and FormPlayerSkill.svelte examples in the report. Read the Svelte binding_property_non_reactive guidance alongside the $derived and $bindable behavior, then compare how the TanStack Svelte Query result is exposed. Done means establishing why this binding is non-reactive and documenting or confirming the supported behavior.