High-output of research papers from China is not surprising at all: considering they pay hundreds of thousands of dollars per paper published in a prestigious journal[1].
It's not too different from the publish or perish culture in US academia, only with a solid cash reward for publishing in peer reviewed journals. I mean professors here are filtered for number of articles here too. Considering the amount of funding that goes to research groups in some universites with the same amount of quality research output as research groups in smaller universities with drastically lower funding, I don't even think it's economically wasteful.
[1]: https://www.timeshighereducation.com/news/chinese-scholars-w...