It's not a problem that is in any way helped/ improved, however, by insisting that trans people must be treated according to their birth sex in all aspects of public life.
That is true. That just maintains the status quo.
However unless you can show that trans women always act aligned to female social norms rather than male, treating trans women as women actively increases the negative impact of these social norms on women and girls, not because trans women are some greater theat but simply because they have been allowed where no other male people are, within the protections that are supposed to exclude people of their socialisation.
And you cannot show that trans women always act aligned to female social norms rather than male, because there is are far too many undisputable instances of trans women behaving exactly along male-socialiased norms.
And ironically, treating trans women as women also actively increases the negative impact of these social norms on women and girls by giving credence to the idea that male and female behaviours are something we are born into not socialised into, differences of the mind and not the body.
And making something worse is worse than just maintaining the status quo.
(You might at first object that those two statements are mutally contradictory. I hope you do. Because if you see that, you see the fundamental issue that we are trying to highlight for you - that the belief that trans women are somehow more like women than other men (itself rooted in sexist ideas about male and female people being different innately not just through our bodies) is not backed up by trans women's actions and statements in the real world).