I can't defend any particular policy of any particular place. I don't think I would call myself a communist, either. But restricting land ownership is a common feature of technocracy in dense urban environments. I seem to recall that the UK does something similar. Even in the US, when you "own" a condo, you are subject to various liens and easements, and can under certain circumstances be forced to sell. China, being rather crowded, likely has created policies to manage land availability.

Communism is, primarily and essentially, about the end of money. Other features of socialist countries are largely the result of how some theorists planned to achieve communism, although they invariably fail. (Some people insist on adding "so far".) Some communists on Quora directly addressed the question of homeownership here:

https://www.quora.com/What-is-the-general-view-on-owning-pri...

Somehow, all kinds of unrelated policies get called "communism" or "Marxism", even when they directly contradict what Marx said (e.g. restrictions on gun ownership). I don't think it's helpful to policy debates to have this syncretistic demon hanging around appropriating the bad name of communism.

Assuming that's true (I have no knowledge of how Chinese real estate works), then that's because China is an authoritarian country that has decided it wants to control every aspect of citizens' lives. That can be a feature of any economic system, if the government is powerful enough, and has nothing to do with communism.