I've not seen any, but I'm also not subscribed to the kind of communities that would be prone to it. I did still manage to get some transphobia directed at me, which is wild because I'm cis.

That's the thing with the fediverse, every instance has a slightly different view of the thing as a whole. That's why picking an instance that aligns with your values matters. You're not going to see much of that on blahaj or beehaw because those users get banned quickly, and problematic instances are defederated as a whole. The matching opposite instances exist too, some are made to be safe heavens for the extreme right, with all the *ism and *phobias going on there.

I recommend people of color to pick instances that supports them, which in turn means they have admins watching their back and shutting down racism quick.

The fediverse will have every problem that plagues other social medias, and it will be worse because unlike Reddit/Twitter, there isn't a centralized authority to say no, that's enough. The only way to deal with it is most big instances saying no and defederating those, but it'll never go away fully, just hidden away.