Svelte 5 Runes - unable to bind child component props directly to parent component props

In Svelte 5, using Runes syntax, I'm trying to bind a prop from a child component to the prop of a parent component directly.

The only way I am able to get this to work is by creating a local state variable in the parent and updating the local state value first, before updating the prop with the local state value.

I did not have to do this in Svelte 4 and this seems unnecessarily wordy and clunky.

What am I missing?

Example working binding:

<script>   let { someProp = $bindable() } = $props();   let localPropState = $state(someProp);   $effect(() => {       someProp = localPropState;   });</script><ChildComponent bind:localPropState />

Example not working binding:

<script>   let { someProp = $bindable() } = $props();</script><ChildComponent bind:someProp />