This was an inevitable outcome of the Cass recommendation to have a broader range of professionals involved in the new clinics' multi disciplinary teams (MDTs).
In my career I have been part of a many MDTs. It isn't uncommon for professionals to take different views (e.g a psychiatrist thinking a diagnosis of autism explains a child's behaviour whilst a psychologist thinks early neglect and trauma is a better explanation). MDTs improve patient care as hypotheses and explorations go wider than would be the case with a single professional/discipline. The team discuss the merits of different 'formulations' and this can often lead to further (needed) exploration.
GIDS (the Tavi iteration) comprised of (or was managed in to being) a team who all signed up to the same doctrine and within the MDTs, no disagreement that went outside the doctrine was tolerated (transphobia). The only accepted positioning was ideological but framed by them as 'ethical'.
The Tavi don't have concerns about the lack of evidence in relation to the types of evidence others are calling for, and will be required when working with non indoctrinated team members. This is because the Tavi think we need to 'decolonise psychology'. Apparently, the Western world has 'limited ideas' about what counts as evidence and these limited ideas (scientific approaches) aren't benign. They serve as a tool for oppressing marginalised groups (such as trans people). Therefore, they feel righteous about not having this evidence and think claims that it should determine patient care are a problem in itself.
It is hard to see how Tavi clinicians can operate effectively in an MDT with clinicians who hold opposing views on what counts as evidence.
The NHS is organised around, and operates from, scientific evidence. I can't see how a service, now under proper level of scrutiny and expected to be aligned with other clinical services, can be based on 'decolonised' evidence. What is coming out now via Kathleen Stock and this article are evidence of this.
I can't see how they can reconcile 'building on what is already working well in gender medicine' (which is the rationale for moving over Tavi staff) with more robust processes (using science to guide practice). The non Tavi staff will sit in MDTs and innocently ask for evidence to back formulations and assertions and will not be able to support them. The ex Tavi staff will not accept any challenge that is grounded in 'oppression' (aka scientific studies).
My money is that the Tavi ideologues days are numbered. The NHS is too strapped for cash to be funding anything that isn't effective or defensible. I am not, however, willing to bet on how long it'll take to get there. I had hoped (but not expected) that due to the time scale of planned opening, they would have just chucked out the Tavi crew when all this came to light. Instead, they delayed opening to try and reconcile irreconcilable differences.