The best part is that this was added in response to people complaining about it not generating diverse enough people, so they made it randomly add different races to person requests that don't specify race.
Why would anyone do that? Like just tell the AI you want diverse people yourself, making it the default just adds more moving parts that could fail(and you end up with diverse nazis or ryan gosling as black panther)
So they do this to try to correct for biases in their training data. It's a terrible idea, and shows the rocky path forward for GenAI, but it's easier than actually fixing the problem ¯\_(ツ)_/¯