I don't think the problem is the UI. Fediverse is more complex by nature than a centralized platform.
You have to choose a server, then an app to visualize (not only online but on the phone too) and there's plenty of alternatives.
If everybody joined the same server we end up with a centralized system and if every large server has to use specific UI what's the point on decentralizing?
I also thought that fediverse had to try to be easier to use but the point is that it's more complicated precisely because the user has more power and hence has to do more decisions.
And I think people have to understand the basics of the fediverse, otherwise people will not stay precisely because it's more complicated. If I didn't care a bit I would be on Reddit not here and I'm currently using both because there's simply much more content there and hopefully with time I can use Lemmy more and less reddit. I'm willing to do the effort of slowly transitioning because I believe in this but people who doesn't care won't stick around.
I thought the fediverse was a way to give back the power to the users. This doesn't seem great. I don't want mastodon to be famous because it's useful to companies but because it's useful to people.
I don't know the details but hopefully they do something similar to firefox https://blog.mozilla.org/security/2021/03/22/firefox-87-trims-http-referrers-by-default-to-protect-user-privacy/