While I agree largely with your conclusion that anti progressive ideas are pushed to undermine progressive spaces, I don't really agree with how you get there and with the examples you choose to arrive at that conclusion. There obviously are actual bad actors, and actual hegemony to get these bad actors into being, but there is also a lot of real people, actually still learning about the topics, or just plainly with a different perspective on some of the issues that you might be discussing.
For it to be an ideology that is self consistent leftism actually needs differences and disagreement, or said in another way: if we were to prescribe beliefs instead of trying to teach them we'd also just be trying to build our "own" authoritarian hegemony. I can invoke successes of or defend the CCP and the soviets just as I can invoke successes of the US or EU or India realizing that all states are fundamentally bad, still sometimes perhaps by accident they do good things. And that examples and mental shortcuts, as well as actual experiments that might be of a socialist nature, are just what they are argumentative tools.
I've been called a tankie just because I see the downfall or backsliding of the US as good thing and don't really accept that china would be as bad as the US has been for the last 40 years or so. Which is perfectly normal for someone who doesn't really reap the benefits of US hegemony, and sort of just ranks authoritarian institutions by size(strength)(wealth) to arrive at a measure of subjective dislike.
It's almost similar to someone calling me a tankie because I purchase Pepsi instead of coca cola on that given day, when we all know I should make my own tea or at least just buy the supermarket/local brand to begin with.
I don't know where you are and what kind of people you meet on a regular basis but to me the simple and fast ways of understanding other people almost never hold true, most of us humans just lead to complicated lives to easily subjectify us. And honestly I wish most leftists would not try to subjectify other people to begin with.