Hey trans femmes, please remember that the kind of person that calls you a man to insult you would never actually try to insult a man that way. Have you ever seen a single one of these chuds try to insult a guy by being like, "You're such a MAN!"? No, that's never happened.
But you've seen them do it to women. Not just trans women, all kinds of women. You've seen these people describe cis lesbians as mannish, joke that feminists are too manly to get dates, all sorts of stuff. When one of these weirdos calls you a man they're doing it because they perceive you as a woman.