In some strongly gendered societies, in order for women to step out of their gender roles they had to constitute a separate gender class. However, this class identity was most likely an imposition put upon them, and something that they would have little say in.
According to the new thinking, this then gets viewed through the gender identity ideology lens which says that someone having a gender role must also have an internal sense of having the corresponding gender identity. In other words, they must be trans.
It's the difference between a woman knowing she's a woman but also knowing that she has to put up with being labelled in some way, that is, an identity imposed from outside, and a woman labelling herself as having a trans identity because that's intrinsic to the gender role, that is, an identity self-generated from inside. Good luck with proving the latter of these. However, as we see time and time again, in the gender identity ideology no proof is ever required for any conclusion that abides by the precepts of the ideology.