They have been doing this for more than a few years now, and advertise in line with the recent guidelines as issued by EHRC.
Dont have the time to find threads now but it is the difference between advertising under the EA (trans inclusive) and under the EA legitimate exclusion of trans women (SSE) https://www.mumsnet.com/talk/womens_rights/5147779-do-the-ehrc-guidelines-on-dsicriminatory-adverts-help-make-sse-job-adverts-clearer-and-even-if-they-do-how-does-that-help-service-users
So it depends whether they have quoted the right sections of the act when advertising.
But as indicated by the thread (link above) none of this helps services users.
There doesn't seem to be any standard by which women services providers say whether their services are covered by the SSE or not.