sadly IT IS because the usage always was misogynistic ๐, it was made to mock fangirls creating OCs that yes technically they're bad written self insert, but people never held male power fantasies to that standards, which is why the term always had a sexist history๐.
neither of these is correct
a Mary Sue is an obvious author insert and has lost all meaning in critical analysis because of overuse and co-opting of its original intent by misogynist internet chuds