I haven't seen this but I suspect it might have something to do with how you are defining gender critical.
To me, gender critical doesn't just mean you believe humans can't change sex. It means you believe sex is immutable AND that gender is harmful.
The way I've seen it described is as follows:
Gender critical feminists:
Accept the reality of biological sex
Reject the legitimacy of gender
Proponents of gender identity theory:
Reject the reality of biological sex
Accept the legitimacy of gender
Right wing conservatives:
Accept the reality of biological sex
Accept the legitimacy of gender
So someone like Matt Walsh, for example, falls within the third category. I agree with Matt Walsh about the reality of biological sex and I think that he often expresses his ideas about biological sex versus gender identity very cogently. For this reason I might follow him, I might occasionally like a social media post of his that I agree with or a clip from his film. But there are lots of things I disagree with him about, in particular gender roles. Matt Walsh and trans activists both believe passionately in performing gender roles; they just disagree on what roles people should perform. Matt Walsh thinks people should perform the roles associated with their sex whereas trans activists think people should be defined according to which roles they choose to perform. Gender critical feminists just think the gender roles are bullshit.
Russell Brand bends gender norms in terms of how he dresses and presents, but he behaves in a very male way, particularly when it comes to his interactions with women. And his sexually predatory behaviour is deplored by feminists of all varieties, but excused by anti-woke types who think this is all just political correctness gone mad and you can't do anything these days without being cancelled.
So it doesn't really surprise me that there are some people out there who overlap with gender critical feminists in terms of their views on biological sex and gender identity, who also consider themselves anti-woke in general, and who also support male people behaving in a male way with male privilege and male entitlement, which is what Russell Brand has done.