Is there a more modern interface like Github / gitlab / gitea?

The one you linked doesn't support the markdown in the post and it's hard to see the changes since it's in like 20 different emails?s.

I usually use the "nested" view: https://lore.kernel.org/lkml/20211206140313.5653-1-ojeda@ker...

In this case, yes. Though it doesn't include replies (since this is just the staging ground the rust-for-linux devs are using)

https://github.com/Rust-for-Linux/linux/tree/rust-next