This is interesting because my son's best friend lives in Shanghai and chat messages sent between the two on Xbox are heavily monitored. In December of 2019 several messages he sent to my son ended up getting erased later with no explanation as to why. He was talking about the virus so I guess that may have triggered automated software?
My assumption was that they had a mechanism in place to enforce this. Very interesting that they don't but perhaps they are trusting parents to enforce it?