* **breaking** Minimum supported TypeScript version is now 5 (it will likely work with lower versions, but we make no guarantess about that)
* **breaking** Stricter types for `createEventDispatcher` (see PR for migration instructions) ([#7224](https://github.com/sveltejs/svelte/pull/7224))
* **breaking** Stricter types for `Action` and `ActionReturn` (see PR for migration instructions) ([#7224](https://github.com/sveltejs/svelte/pull/7224))
* **breaking** Overhaul and drastically improve creating custom elements with Svelte (see PR for list of changes and migration instructions) ([#8457](https://github.com/sveltejs/svelte/pull/8457))