“Tankie” is a strawman. It’s a pejorative for Marxists and anti-imperialists, filled with falsehoods and contradictions. The purpose of calling someone a “tankie” is to turn them into this strawman in the eyes of onlookers, it terminates the conversation. An example of this is you claiming so-called “tankies” think Russia is still a socialist country governed by a communist party, which is absurd. Russia does maintain strong ties to socialist countries like China, does oppose the western Empire, and does have rising socialist sentiment in the broader population, but absolutely isn’t socialist.

The PRC is socialist, though. Public ownership is the principle aspect of the economy, and the working classes are in control of the state. Huge state owned industries are the backbone of the economy, while mixed forms of ownership make up the small and medium firms. Socialism isn’t the absence of private property, even under Mao and the Gang of Four there were still large numbers of private firms.

As for what you call “authoritarianism,” what we communists support is the working class using state authority against capitalists. Authority should be used by the working classes. This confusion of yours is why you misunderstand China. The PRC is by no means “late stage capitalist,” rather it’s relatively early in socialist development:

All in all, I suggest you listen more to these so-called “tankies,” rather than letting your imagination run wild.