In my opinion, it is called subtle discrimination. Unlike blatant discrimination, which consists in openly humiliating a member of a minority based on their personal traits, subtle discrimination is much more perfidious, as it is not always easy to point finger at it or to legally assess it. Sometimes, it even happens as a consequence of seemingly good intentions. For example, if I use lower standards to grade Afro-Americans in a class of mixed students, it still means I assume they are less capable or educated, even if I do it because I know that they had been oppressed and had historically had less chance to educate themselves.
