I think the rise of the Omnicause is part of the gentrified left having mostly abandoned class and economics as its central driver, and adopted Foucauldian postmodernism and critical theory.
What you get instead of class is an unthinking identification with any group identified as the underdog, based on an idea that they're all rebelling against the same power structure (call it capitalism, Yankee imperialism, the cisheteronormative patriarchy, The Man) and are therefore part of the same cause. How you get your list of approved underdogs is another matter, and it doesn't do to question this.
That's why you not only get Palestine flags on trans protests, or trans flags on pro-refugee protests, you get constant attempts to rationalise why these are actually the same thing. I stay in touch with what lefties are saying, and I'm currently hearing stuff like "those Epping mums who say they're worried about a migrant hotel near their daughters' school are just repeating racist lies about brown men's sexuality which are the same as terfs scaremongering about transwomen in toilets".
You know anyone in the left activist scene, you hear this sort of reasoning constantly. All their key issues are connected and somehow Palestine is the crazy glue that connects them.
And because of social pressure, people I know who'll privately admit that the left has both a misogyny problem and an antisemitism problem can't bring themselves to think that maybe their pet issues of trans and Palestine provide cover for lots of nasty impulses to hide in plain sight.
The right has its own omnicause tendencies, but they seem to me to be less severe, because the right is inherently less ideological and less driven to make every issue part of one consistent narrative. So someone like Douglas Murray is massively pro-Israel, but he doesn't feel the need to mention Israel when he's writing or speaking about unrelated issues. Compare that to say Owen Jones.
I'm not sure I'd say that I've moved right, though some people would say that. It's more that, having been cancelled from the left, I'm now free to not take all my opinions as a job lot. I can examine things I thought I believed, think about why I believed them, weight up the views of people I wasn't supposed to listen to, and maybe conclude I was wrong about certain things.
And finally: if people can lie to you that men are women, what else are they lying about?