It's not overwhelming, but I see occasional "eruptions" of Tankies and their ilk on posts and in communities where you wouldn't expect to see them. Maybe just an organic thing where they see each other coming out of their closets and decide to pile on when they get the chance, but still kind of annoying and not something that's easily preemptively blocked.
That said, this is hardly unique to the Fediverse. There's stuff like that in social media in general, the Fediverse just happens to have that particular flavor for reasons of historical happenstance.