The influential online community that gave rise to social movements like #BlackLivesMatter is now a "digital diaspora” in search of a new home.
As I understand it, one of the major issues with moving to e.g. Mastodon is that the Fediverse doesn’t implement blocking in a way that you’d expect, at all. It’s effectively impossible to block someone the way we’re used to blocking in places like Twitter, Instagram.
I have also heard a lot of stories from Black folks about anti-Black sentiment on Mastodon.
Blocking seems to work fine on Mastodon (kbin is a whole other story; it is a trash fire), but the big thing was the Mastodon HOA (the Mastodon users who will rock up to tell you you’re doing Mastodon wrong and yell at you for wishing for something like quote tweets) and some servers insisting Black folks put posts talking about racism they experienced behind content warnings. Plus some just blatant racism. Being told to just make your own server or move to a new one hit like needing a dang Green Book just to be on the platform.
A lot of Black folks who went to try Mastodon during the first round of migrations off Twitter after Elon bought it got chased off of Mastodon, and they warned folks away.