1. Chinese researchers are catching up and increasingly producing good papers.
and:
2. There is a lot of low-quality junk science spam coming out of China.
Are entirely compatible. Both can be true at the same time.
I don't really know about scientific papers, but the high number of Chinese patents is generally considered a fairly useless metric files mostly for "CV reasons" rather than representing any genuine invention (see e.g. [1]). But here too, "China is producing tons of trash patents" and "China is catching up on innovation" are entirely compatible.
For what it's worth, my impression is completely different from yours. A significant share of major findings are now coming from China.