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.