As a person of color, I think Mastodon, generally, has been a way greater place than Twitter as far as harassment and the like. I also think the way the Mastodon tool is setup (decentralized, good moderation curation tools, not run as a capitalist corporation) is great.
That said, 'The Street Finds Its Own Uses For Tools', as some old author guy once said. It's hard to say what Mastodon will look like if/when it gets to user counts near Twitter's. I am hopeful, though.