Life is too short to put up with shit like this. Or to stay and fix the problem. Maybe let them know politely the reason when you leave, but that is likely to fall in deaf ears too.
I have been living in Asia for a while, indeed diversity is not seen as anything useful. It's not considered a criteria to be taken into consideration.
I have worked in diverse team and I have worked in a monoethnic team. I haven't seen any difference whatsoever in term of performance.
From my own experience I like working in a monoethnic team. And I like working within a team with a little bit of diversity. But when diversity is going too the roof, then my degree of joy at work start declining.
Being in a team where people are black or have vaginas is devoid of any value to me. And I tend to leave any companies that seek to optimize these criteria because I find the idea of hiring based on gender, sexual organs or racial consideration to be intellectually insulting.