They say something objectively horrible. When you call them on it, and they say “yeah I said that shit, come at me bro”, that is also not gaslighting. Maybe it’s being a jerk depending on the thing, but it’s not gaslighting.

They say something objectively horrible. When you call them on it, and they own their mistake, apologize sincerely, and explain their mental state at the time the thing was said, but express genuine remorse for having said it, that….is NOT gaslighting! It’s growth.