I'll agree that his recent depictions of black people are on the "wtf are you doing, stop it" level but Bengus has such a long history of exploring and mastering different art styles over literal decades (drawing plenty of black people well over the years) that it seems more like a particular stylization style that failed.
He's making a choice to portray black characters in ways he doesn't portray other characters. Yeah, his style has changed, but that stylistic change doesn't explain the sambofied/otherized black characters and all other characters not being racist caricatures.