Name calling others weak and fearful doesn’t help.
High testosterone levels matter. For some sports- cycling, sprinting, wrestling, girls flag football, the impact of tripling the testosterone levels is very significant. We have women’s weight lifting record that will never be broken. The women who set them were on testosterone, and had muscle mass they could never have built without it. Lance Armstrong won several titles by cheating with testosterone boosters. It is ridiculous to pretend that high testosterone levels are not a factor in sports. The question is how long does the effect last and does transitioning reduce the effect to the point that it is fair for trans females to compete as female.
A good study on the effects of transition on athletes would help. I’m not sure there is any valid way to do such a study. The numbers are so small, and the possibility for complicating factors is so large. For example, there has to be a psychological effect on effort put into training, but we don’t know which way it goes. ( An athlete might train extra hard so she can fit in by helping her team. Or she might avoid the weight room so that she looks less male.)
It also matters that, among youth, the word transition does not necessarily mean surgery. You are often talking about an athlete who has culturally transitioned, is on hormones, but has testes. Hence the testosterone question.