Reports are the big one. Ideally, with inline context, and the ability to remove the content in question from the report queue itself, rather than having to navigate to the page (though that should also be an option)

Also, if there was a way of highlighting reported comments inline when viewing them (this isn’t an out of the box lemmy feature though, so I’m not sure how feasible it is).

Also, it would be nice if you could put a bit of text in the reporting screen encouraging people to provide context/explanation of why the post is being reported. So often, people don’t include any/enough information