As far as you Bernie/Biden experience goes, I completely believe it. In fact, I'd be really surprised if it was any other way since Bernie's major moment was a race against a female candidate and later competed closely against two other female candidates, one of whom made a pretty explosive allegation of sexism against him. Whereas Biden and his supporters (who are themselves much less active as participants in political discourse) have never been in that situation. I would personally predict that in, say, a contested race between Biden and AOC, you'd see far more sexism from centrist Biden supporters against the left-wing AOC than you saw from left-wing Bernie supporters toward Clinton. But that's conjecture.