The Mastodon v5 UI is pretty awful. I can't think of anything that could be described as an improvement. That's on a mainstream browser; it's essentially unusable with Pale Moon.
It's so bad that I would effectively leave any instance running it.
(Effectively because I don't think it's possible to navigate to the right point in the UI to actually leave...)
@ptribble I'm trying to understand how to deal with this, when Mastodon 5.0 will be out. I'd usually like to provide other options. If needed, maybe an official littleFedi instance.