The definition of a woman includes a man with a GRC.
Not sure what you are referring to but currenlty, and this is the law the Labour Government defends (as they created it) and stopped Scotland's attempt to bring in self id is that
The UK EA allows for 2 types of women. One is a "legal" woman ie a man with a GRC, but there are also biological women who are (aren't the kind) allowed when "proportionate" single sex (ie actual biologcy) services, support etc..
The FWS court case was about trying to get a court to say that the use of the word sex in the EA must / should mean biology. Although as the Lady Haldane ruling pointed out the fact that the GRA was allowed to undermine sex as a protected characteristic by saying if you have a certificate you are legally the opposite sex to the one born.
So some think this court case (actually about equal representation on boards of companies) would fail because the law as written is the law, which is what Lady Haldane found.
Which is why some thought the best thing is to get MPs to clarify the meaning of the word sex (which even the EHRC has said is a mess) in the EA.
But as we know although this was discussed by MPs (following petitions) the next stage of "progressing" this was being done by Kemi Badenoch who for instance sent round directives about single sex toilets and a survey to find out how many actually understood the SSE.
But as she is gone, and Labour love the law as is (they wrote it!) we are now having to rely on Judges saying that although the law as written is that there are 2 types of women it practice this is discriminatory against biological females and so should be amended to say that the word sex means biology.
Which means GRCs become meaningless.
Not that this would stop TRAs from attacking something so transphobic.