Every single story you've ever been told about trans women automatically being better at sports than biological women is a lie and you buying it is evidence of 1) Your stunning ignorance of human biology, 2) Your own bigotry against women, transgender or otherwise.
So let's say a biological male who identifies as female but hasn't transitioned. Should that person be allowed to compete in women's sports?
If they identify as female, they are transitioning. If somebody identifies as a woman, that makes them a woman.
There was a standard for this in most of athletics, and that was if a trans woman had been on hormone therapy for a year and had testosterone levels in the normal cis female range they could compete in women's athletics. It's what Lia Thomas did, and she was still crucified by the right.