Fore some times, mastodon has been unsafe for black and other minorities users, the peoples impacted by this have been complaining about it openly, emphasizing the lack of good moderation tools to make instances safer. The 
s on the dev team and userbase however have essentially plugged their ears and refused to listen, and instead engaged in bad faith, tone policing, minimizing racism, dismissing the testimony of black users, and telling them to "curate their experience better" with filters and blocks (even though a big part of the complaint is that this doesn't work).
Seeing this, some black peoples who have been complaining about racism on mastodon and the lack of security features to deal with it have taken things in their own hands and made a fork of Mastodon named Awujo.
This sounds vague of course, let's see how it develops. Implementing better moderation tools shouldn't be that hard. Reducing technical bloat sounds not that easy, it needs time. Probably a lot of refactoring will be done, if an increase in performance is expected. I am looking forward.
I am not familiar with mastodon but it probably also don't have a way to add plugins or similar things. If the developers don't want to add more moderation tools, than I would also just fork it. But isn't it to much work regarding the optimisations that have to be applied? I mean, it does sound like that the code basis will start to differ fast from mastodon.
And why didn't the mastodon developers want to implement these tools? I would understand, if there were technical reasons for it. I know from myself, that applying some changes may may also be not easy to apply, because the software was designed in a specific way (Or just a result of technical debt). But they just didn't want to do it?