If you Google "rishi sunak equality act sex", you'll see a bunch of results from last month reporting that Rishi Sunak raised the prospect of amending the Equality Act to clarify that sex means biological sex.
You'll also note that the results are heavily skewed by the trans activist side.
For example, the Gay Times reports that, "The UK's latest Prime Minister Rishi Sunak is reportedly planning to review where transgender rights stand in the Equality Act 2010."
Prick Pink News goes further, reporting that, "Rishi Sunak 'wants to gut trans rights from Equality Act'."
All because he said that the protected characteristic of sex should refer to someone's actual, biological sex, i.e. the innate characteristic they can do nothing about and the basis on which 50% of us are routinely discriminated against, and not someone's "legal sex", a mechanism by which male people can choose to be called female but do not lose any male privilege, and female people can choose to be called male but do not gain any male privilege.
Confirming that sex should mean your actual, real, biological sex isn't taking anything away from trans people, who already have all the same rights as everyone else, plus a few more rights that no one else has, and who already benefit from their own, separate, protected characteristic.
All it would do is ensure that members of the female sex are entitled to sex based protection.
Why would trans activists object to that if, as they claim, trans rights are not in conflict with women's rights?