"Starting September 1, 2021, the Chinese government will require that any Chinese citizen who finds a zero-day vulnerability must pass the details to the Chinese government and must not sell or give the knowledge to any third-party outside of China (apart from the vulnerable product’s manufacturer)."
Two ways to look at this:
1. China is working to prevent 0 days falling into the wrong hands (dark web markets, hacker groups)
2. China wants to exploit these 0 days for its own benefit
For a country dead set on becoming the world's #1 super power in the next decade or two, option 2 is probably the most likely.
New Law Will Help Chinese Government Stockpile Zero-Days | SecurityWeek.Com