The allegations that Olympic boxers Imane Khelif and Lin Yu-ting failed an eligibility test for women's competition have been made by only the International Boxing Association.
You could also argue that historically ( in the west at the very least ) it was partially to stop “women” from competing in “men’s” competitions, not because of a difference in physicality but because of a difference in societal expectations.
Or sometimes it was just done to stop women from beating men.
In the 1992 Olympics, a woman won gold in the mixed sex skeet shooting category, beating male competitors.
In 1996 women were barred from the erstwhile mixed event, but did not get a separate category either. Only from the 2000 Olympics a separate women’s skeet shooting event was established.
Or sometimes it was just done to stop women from beating men.
In the 1992 Olympics, a woman won gold in the mixed sex skeet shooting category, beating male competitors.
In 1996 women were barred from the erstwhile mixed event, but did not get a separate category either. Only from the 2000 Olympics a separate women’s skeet shooting event was established.