It’s common to hear that the USSR got over extended supporting global communism too much but realistically they could have kept that up had they not had the economic problems they did.
China today has much better economic positioning than the USSR for a variety of reasons so I really think them not helping more is a huge mistake but part of it is that while they defensively an in their region they can likely match the US they can’t do that far from home right now.
I’m optimistic this could change as China is able to get to parity with the US on military power projection. I know they have plans for building nuclear powered aircraft carriers which is what they need realistically if they’re going to actually militarily intervene to help say Venezuela or Cuba due to their distance from China.
IMO the next 10 years are going to show if China is actually willing to take on the mantle of the leader of global commmunist movement like it needs to.
Russia/Putin only get critical support from leftists because they tend to support the anti imperialist block through trade and weapons sales and by countering NATO. They’re pretty clearly not going to revive communism and the anti LGBTQ stuff is horrible.
Putin isn’t supporting the block that because he secretly wants the USSR to return it’s just the position they’re forced into because the west won’t let Russia join as an equal. So they’re in this weird spot of being a capitalist country that could be as bad as the US if they had the means but end up being an ally because they’re rejected by the West and don’t have the means to rival the US as a leader of world capitalism.
Material conditions could change in the future though and I’m sure there will be some split down the line between Russia and AES countries unless Russia is able to have a 2nd October revolution.