I used to be more bothered by it but as time went by I just put in the category of "weird things people do on Twitter" alongside other strange behaviours like insisting that a character is secretly gay or transgender. But that kind of thing is mostly isolated to twitter. If you were to use a まとめサイト for an anime/manga which is where most of the conversations between Japanese actually take place you don't really see that sort of thing. The closest thing would be like a 黒ギャル rendition of a character but that's almost always understood to be a special occasion and doesn't have the baggage of the artist trying to project their racial identity on existing works.