https://www.scmp.com/economy/china-economy/article/2182963/chinas-birth-rate-falls-again-2018-producing-fewest-babies

https://www.scmp.com/comment/opinion/article/3018829/chinas-population-numbers-are-almost-certainly-inflated-hide

https://www.scmp.com/news/china/society/article/2052220/chinas-demographic-future-has-big-problem?edition=hong-kong

You also cannot trust China's official population data.  It is highly skewed to make local officials look good.  The actual population of China is probably far less than official numbers.