Sound null safety is one that most languages don't have.
Also looks like they're going to include static meta-programming, so you can metaprogram at compile time rather than runtime like many languages [0]. With this, many language features can be implemented yourself rather than needing the language maintainers to do so, such as adding dataclasses or (React-like) hooks. And if the state of the art changes, the language won't need to be redesigned or more stuff bolted on, you can just swap out the old language feature (as a package) and swap in the new one.