I don't understand all the nonsense about so-called "blackface" when it is just simple dress up - nor do my African friends. Seriously, at least the Nigerians and other (usually West) Africans I have contact with find the whole concept of being offended by someone dressing up as someone else, no matter the make up used, as totally ridiculous and "American." Means the US, again, trying to enforce their view of things on everyone else. And that's lead to a stereotype about American blacks which in itself is another issue. At least for the US folks, their issue with black makeup has a historic base, however flawed their reasoning now is.
I find the whole idea that something could be "appropriated" in RPG ridiculous. By trying to make such things an issue, you could as well forbid crossgender. The whole point is to be able to play anything you want.
I have a lot more issue with cultural falsification, that is dressing up as something or the other while not having a clue what you are doing and what that supposed culture is all about, as in mentioned "Indian" or "African" costumes or the Lederhosen German or, independent of costumes, those "Indian" dream catchers and other bits and pieces of other cultures, which usually have little to do with the original meaning they have in the culture in question and often promote prejudice and stereotypes long disproved.
This is something that can't really happen in fantasy or sci-fi RPG though, unless you complain about someone playing a too dominant male Drow, because as everyone knows they are all matriarchal

It is all made up stuff, no one can, with any sanity, have an issue with it. The only exception may be in LARP when a setting uses existing stereotypes, as for example "gypsies" or "plains people" which are often nothing but stereotyped real world groups. Never lead to any issues I know about, but you never know.
Now, in a real world (with or without magic) style game, I am usually very careful as a GM as to what I allow in my sessions. Not because my players would complain but because I need things accurate (very obsessive about that). Someone wanting to play a member of an existing religion or culture (even if it is another white culture) needs to put some research in so we don't end up with a James Bond style Voodoo cult/Italian Mafia mockery or the like. Nothing to do with appropriation, it's just a game everyone can have fun with without insulting anyone.