Not t true. I don’t have the reference, but I read 10 or more years ago about an affluent community in the midwest whose black students greatly underperformed their white counterparts. The parents hired a black researcher and his final report said exactly that, that many black students didn’t want to appear white and also there were negative consequences for trying to do well. The parents thought it had to be racism and wouldn’t accept the results. The guy was a sociology professor at a college in CA.

For more annectdata, this same thing was happening at Berkeley High School around the same time. First hand knowledge from parents of students.