The official app is a horrible user experience, but the bigger issue is that most of the content is fake. Between commercial shills, political activists, social-media marketing groups hired to “increase engagement”, and various other bad actors, the site is no longer useful or differentiated. The only places that seem unaffected are smaller private subs.
I don’t know how the fediverse will prevent the same thing happening. The bad actors are just going to follow the eyeballs. They don’t care which platform is used to host their actions. There was already an instance of a group of new kbin accounts being used to mass upvote topics to appear in the hot feed here.