link to the article. it’s hard to form thoughts on just the headline alone.

China is prohibiting Russian Boeing and Airbus aircraft owned by foreign leasing companies from flying through its territory.

According to the Russian news outlet RBK (RBC Group), the ban affects equipment whose legal status has not been confirmed following Western sanctions

I think this is pretty self explanatory, they only banned the planes which are, because of the west, not fulfilling chinese regulations.