You've given me a lot to think about but I do want to clarify my personal views a bit. I'm not anti-Marxist, I don't believe authoritarianism is inherent to marxism, just that those tendencies are present.
For context, Marx and Engels were constantly referred to as authoritarian, to the point that Engels wrote On Authority to counter the notion entirely. Authoritarianism is typically ill-defined, or used to simply refer to any use of the state apparatus, it's a moving goalpost. I recommend reading Why do Marxists Fail to Bring the "Worker's Paradise?" because judgement of AES states is usually done in an idealist manner, rather than actually looking at the structures. It's a 21 minute article, I highly suggest reading it, if nothing else.
From my perspective authoritarian communism is to my right, so I don't see it as left-punching, but I think the left-right metaphor is reaching the limits of its' usefulness here.
It isn't about direction, you're correct that left/right reaches its limits here. Marxism is on the left, period. If you are punching left-wingers yet giving liberal right-wingers a pass, then you're running into issues, hence why I suggested just making it an explicit and exclusive Anarchist community. Grad punches Anarchists, but also punches liberals, it's strictly Marxist so it doesn't run into issues with cooption or confusion.
Vladimir Lenin referring to "left-wing" communism as an infantile disorder is more in the ballpark of what I mean when I refer to authoritarian communism.
Have you read it? Lenin isn't just saying leftism is wrong, Lenin was one of the most radical Leftists in history. Lenin is specifically referring to Ultraleftism, which is idealist in nature, and not Materialist. It's a failure in understanding the Material Conditions of society and trying to achieve Communism through fiat, without developing the productive forces to be able to achieve it, which has historically run into massive issues. Lenin is correct here, you can't pray Communism into existence.
Huh, interesting. Probably weird fediverse shenanigans!