Tankies here are just anti-west. That's literally it. So Russia, China, North Korea and now Iran are all good guys because they're on the other side of the US and NATO. Or if not the "good guys", then it's a very complex situation where Russia isn't an imperialist state, but in danger from NATO surrounding them (even though they have nukes for safety, we'll ignore the nukes), and so they are practically forced to defend themselves by bombing residential buildings in Ukraine.

I would assume that the whole marxism aesthetic is just because the west has always been capitalist, so they just take the inverse of that.

Marxism-Leninism isn't about being Marxist or Communist. It's about supporting whatever's politically expedient for the current leader of Russia without critical analysis.