China CO2 emission increased a lot over the last 20 years and it is growing every years. Not decreasing but increasing. The IEA estimate says China’s CO₂ emissions reached 12.6 Gt in 2023, up 4.7% from 2022.

On the other hand U.S. CO₂ emissions decreased slightly between 2022 and 2023. About 2–3% (from 4.79 to 4.68 Gt)

[1] https://www.iea.org/countries/china/emissions

And then in 2025 it was exactly the other way around. China's emissions decreased, the US's increased.

https://news.ycombinator.com/item?id=45108292