4chan’s /b/ board has a thread pretty much daily for 20 years at this point, filled with pictures of black men with large penises and baiting text. (Obviously written by a white guy with a fetish, but pretending to be black with stuff like “jealous white boy?” etc. )
It’s gauche to be mentioning Emmett Till on a porn board, but you can’t divorce the obsession with black men fucking their wives/girlfriend from the fact that many black men were horrifically tortured and murdered on the accusation that someone fucked (or even whistled at) a white woman.
Another aspect is that cuckolding is more sexually transgressive than cuckqueening, in the same way that polygyny has always been more common than polyandry.