I've seen a lot of people (not here; on Earth in general) not care when something they do hurts someone, and they keep doing it. Some of them continue just to upset the other person. That seems sadistic to me, and not the good kind of sadistic. If something I said or did deeply upset someone because they have scars, I'd apologize and would stop. The same principle goes towards addressing people of the name they want to be called if it's different than their birth name, and using their preferred pronouns.
This isn't exactly a trigger, but I'm not into the thing where people use insults as terms of endearment for friends. On a personal level, it just grosses me out and I don't want to be talked to like that. So, if I made a friend who did that, I'd let them know.