I think it might just be protectionism in order to benefit domestic film producers, this has been a policy of theirs for a while that they've recently doubled down on.

https://news.cgtn.com/news/3d6b6a4d786b444e/share.html

https://deadline.com/2021/11/china-outlines-14th-five-year-plan-for-movies-whither-hollywood-does-that-market-still-matter-1234875506/