The 3 worst ones that immediately came to my head were Kingsley Shacklebolt (he’s Black), Cho Chang (she’s East Asian), and the Patil twins (they’re Indian). I’m sure there are others that are just as bad though, alongside the numerous other stereotypes in the stories (the house elves, the goblins, etc.).

I read those books as a child and then a few years ago I rewatched some of the movies and realized how awful the subliminal messaging is.