"Cultural Marxism" is a (centuty old?) antisemitic conspiracy theory / rhetorical trope that the author of the tweet is comparing current antisemitic trends in "GC" speech & conspiracy theories to. I don't think it has anything to do with actual Marxism. I.e. anti-trans people are pretty much recycling antisemitic arguments after having already recycled Anita Bryant era homophobic arguments.
(no subject)