Today, when DALL-E was still free, my Dad asked me to try a prompt about the Buddha sitting by a river, contemplating. I did about 4 prompt variations, and one of them was an Asian female, if that gives any idea about the frequency (I should note that the depiction was of a young, slim, and attractive female Buddha, so I'm not sure they have the bias thing licked just yet).
In my little testing, diversity in ethnicities was achieved but not realistic given the context. I also got a few androgynous people as I asked for a male or a female and another gender was appended.