My daughter’s Chihuahua is also racist. Doesn’t much like anybody, but really, really hates black people.
I remember Vietnam era vets saying that the dogs of Vietnamesse families hated all of our soldiers, white or black. As dogs have a sense of smell that is 2500% better then ours, the pick up the dietary and grooming product differences and see those scented differently from their core “packs” as outsiders.