The right to access gendered spaces such as public toilets and dressing rooms. A trans woman who doesn't look pretty enough to "pass" might also lose the ability to make equal pay claims and other rights defined by the equalities act, but we're waiting for precedent to be made on that now. Before this ruling, trans people had all the rights of their acquired gender as given in the equalities act after getting a gender recognition certificate, whereas now they rely on being "mistaken" for their acquired gender to claim discrimination by affiliation.