I feel like if you're trans and an athlete you should be able to play sports with the gender you now identify as.
That's going to make it hard for those born female to compete.
In cases where people are segregated due to gender, I'm all for (in most cases) people being grouped according to how they identify. When people are segregated based on physical characteristics, then I don't think that makes sense. Allowing a male who has not transitioned to compete would completely defeat the purpose of women's sports. If someone has transitioned, then that may be alright, if the data shows their advantage has been mitigated.