I coached high school boys and girls crew. NCAA rules allow an adult male athlete to compete as a “hormonal female” after only one year of testosterone-lowering therapy. This may lower their times by 5 to 10 percent.
So a mediocre male athlete can beat many elite female athletes if their 95 percent times are better than the times of their biological female competitors. A mediocre male athlete can more easily medal as a “hormonal female.” They can game the NCAA rules to do this, then switch back to being “hormonal males.”
A biological adult female cannot take testosterone and compete as a female, and they have little incentive to compete as a “hormonal male” against adult biological males.
There is a rather straightforward solution. Change the rules: “Hormonal female” adult athletes should compete against other “hormonal female” adult athletes, not adult biological females.