So, I'm not an authority. But I think some people are confused about what "gender critical," means. So I want to provide a bit of background.

The "gender" in "gender critical" does not reference the recent transgender craze, but rather it comes from an earlier line of thought in radical feminist discourse.

"Gender" was believed to be a system that oppressed women for the benefit of men. Things like beauty standards, deferential treatment of men, which work was "women's work" were thought to be part of this system. As were more extreme female/femininity practices I'm sure you've all heard of.

When GC says they are "gender critical," it's meant to mean all systems of gender. The transgender stuff is only the latest manifestation of that older system.

So if you think there is a problem with the current transgender stuff, maybe you would say you are "opposed to transgenderism" or "transgender ideology". If you believe all/most historical gender practices have oppressed women for men's benefit, then that would be a "gender critical" position.

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So why does "Gender Critical" focus so much on the transgender issue if that's not really what "gender" means here?

Well, a while back there was a growing split in feminism. There was a group who tended to think pornography was always bad, that femininity is meant to oppress women, and that men should not be considered "women" for the purpose of feminism under any circumstances, even if they take cosmetic and/or hormonal steps to try to be more female. Eventually with the rise of aggressive transgender activism, this group of women was pushed out from other feminist spaces, primarily because of the transgender issue. Thus they created their own subs, and remain embattled with the same contingent over these same issues.

That's my understanding at least, though I think I've probably got an incomplete understanding of where the movement came from.