Short answer
Sexual preferences.
Longer answer
The thing is, you can’t take people’s word about them being white/black supremacists or not being racists just like that. We humans are social animals. We’re tribal creatures. Often, we’re conditioned to say things and act the way that deep down inside we don’t like at all.
Remember all these priests, prominent Evangelicals and other Conservatives who were blasting sodomy and loose morals—only to be caught out privately enjoying carnal bliss with members of the same sex?
Especially in modern world, proclaiming yourself an anti-racist, WASP nativist, Antifa, or white/black supremacist is a declaration of allegiance to your tribe. We want to belong, so we often parrot what our reference groups say.
“Hold with the hare and run with the hounds”, how about that? Deep down inside, we may hide something very different, invisible to everyone else. I spent half of my life in the USSR, this was how things worked for almost everyone back then.
This is why I believe in horny. That’s your touchstone. Nature made it rock solid against social conditioning. Even buried deep and hushed down by all the voices in your head, it’s still down there, alive and kicking. That’s the surest identification of your true self.
Hey, there’s even some research about it. For example, Tal Nitzan from the Hebrew University linked the low rates of rape of Arab women by Israeli soldiers to their sub-human, abject status in the Israelis’ mind.
Below, a scene from a Stalinist propaganda musical “Circus”. It’s about an American show girl who got a child with a black man and was harassed for it by evil Capitalist Westerners. In the movie, the lady found refuge and happiness in the USSR. Yet somehow, her new love interest happened to be a snow-white Soviet man.
In a way, the Soviet Union didn’t really pass the gut test for non-racism. For all the anti-racist propaganda, our mass culture never managed to produce a compelling love story that would involve a black person of either sex with a Soviet citizen.
In post-Soviet Russia, our sexual preferences haven’t changed much, if we trust the stats provided by PornHub. Below, their stats for the last decade:
As you see, “interracial”, “ebony” and suchlike are nowhere to be found, in a clear contrast to East Asian content. How about regional differences?
Our Muslim compatriots in North Caucasus seem to have a preference for Mediterranean/Middle Eastern ethnic types. The Far East, with a visible presence of local Asian minorities as well as guest workers, demonstrate a taste for East Asian flavor. But Black is absent.
How about about the most popular stars?
Not being an expert myself, I see that ethnic diversity here doesn’t go beyond Mia Khalifa (Lebanese) and Asa Akira (Japanese). Both seem to be rather white in skin color.