Feminisim includes defending sex-based rights. sex is one of the 9 protected characteristics under the EA.
EHRC in this report:
Most political parties are considered associations under the Equality Act 2010. This means that, by law, they must not discriminate against, harass or victimise members, associates, guests, or those wanting to become members, on the basis of a number of protected characteristics
across all parties against anyone standing up for women's sex-based rights, jewish rights or any right under the EA, are facing calls to get the whip withdrawn (Rosie Duffield, Kevin Price), or hounded out of their job (Luciana Burger)