I've just googled them and found this on their website.
About Us
The Trans Advocacy and Complaint Collective UK is a grassroots organisation started in 2024 by a pair of dedicated trans women to advocate for trans rights, address transphobia, and ensure that the voices of trans people are heard across the UK. Since our inception, we have grown to a membership of over 120 people.
Our mission is to create a united front for all trans, detrans, non-binary, queer, intersex and cis allies to push back against discrimination, hold media accountable for transphobic content, and ensure that our voices are heard. If you’re passionate about activism, need support, or want to help make real change, there’s a place for you in our collective.
We are an apolitical organisation, so we cater to all.
So basically a tiny trans start-up with inflated ideas of their own importance.