What 'rights' would be repealed?
Protection from discrimination, harassment, violence, equal access to marriage, protections in law, work related protections, etc etc should be absolute for everyone regardless of race, sex, age, gender expression, sexuality, disability, etc etc.
The mistake of the GRC was to create a legal 'fiction' for a specific group, largely to avoid legalising gay marriage. That equality for marriage has now been established in law in other ways, and is no longer an issue. The EA now also specifically provides protections for trans people.
As far as I understand it, the desire is to repurpose the GRA to confer the legal status of being a woman on any male born person who signs a self declaration (which in practice will mean any male who enters any female space since no one will check this at the door, the person will be assumed to be self declaring by the very act of entering). So legally changing the definition of women to include male born people, removing the protection of single sex spaces for women, removing the right of women to have facilities, spaces or recognised identities apart from men.
The rights being 'repealed' are all womens, not transwomen's. In fact, by stealth, this will create a hierarchy of protected characteristics under which women, religious beliefs, disability and safeguarding all lose if a transwoman is involved.
I have mentioned to my MP that it is also much easier to create law than it is to undo it, once these 'rights' that someone must have full entitlement to the category and resources of a protected social group purely on their subjective feelz instead of the objective, provable reality of belonging to that group, then it will be very easy for those entitlements to be exploited in all directions (hello transdisabled people demanding benefits, carers, hoists, hello transage people demanding access to nursery places and vouches, we already have transrace people taking places set aside for BAME people) and very, very difficult to repeal the mess of law that enabled it all.
This is a very good reason to stop, think, increase 'rights' and the law framework gradually while monitoring impact, and not to rush straight into legal hell with a glow of good intentions.