Aside from the obvious alt-right/nazi/anti-sjw instances (which most instances block) I pretty much don't bother engaging with anything from mastodon.social or cyber.space or the other big "flagship" instances because like... they're so bad lol. Many of the smaller instances don't even include them in their list of "known" networks.

I guess Mastodon is crumbling in the sense that the flagship instances aren't in a very healthy place, but the idea of a flagship instance was probably a mistake in the first place anyway.