I can understand an argument about leaning towards London (although in fairness London is massive and also is where a huge portion of the industry is situated) but the argument about “this lack of diversity” doesn’t make sense when you’re talking about black artists. As has been pointed out before, Ezra Collective isn’t an all-black group (and neither is Young Fathers, who are from Edinburgh). Wolf Alice won in 2018 and I don’t believe they have any black members. And, as @adayasatiger pointed out, it’s not like the winners have been predominantly from a particular genre of music.
So what is the lack of diversity you’re talking about? Your post comes off as saying “there are too many black winners” without acknowledging that there’s actually quite a lot of diversity in the recent winners.
There's some diversity in terms of music genres, but even then has there ever been any heavy metal bands nominated?