Maybe because Africans generally act like assholes? That ain't racism. Jamaicans, Afro Latino, they cool. But Africans. Girl, I tell you. There's a divide. Afro Latino, carribean blacks, and Americsn blacks? We have a kinship. They were also former slaves and kind of roughly go through the same stuff. But Africans? Lol. Almost every African I've met has been rude but there's exceptions, but generally their manner of conduct will create an abrasive reaction from many black people.
We just don't like each other, have completely different cultures.
This is like calling Chinese hating Japanese people "internalized racism". Life is much more nuanced than that.
That said I'll always treat an African with respect. But my experience? Being from a city mostly made up of Africans? It's really negative and I admit I say,"oh boy, here we go" when I realize they're African.
Oh, and these Africans are usually Nigerian, so maybe it's that. Who knows.