Peak consumption for a population is 45-54, when income is highest and people are having their 1 kid. Once retirement hits income is generally fixed as people rely on pension or savings. They also depend more on state services like healthcare. In China, this also means depending on their 1 child.

It’s not really possible to say “China’s fundamentals are fine” because China’s fundamentals look like nothing the world has ever seen. It’s not clear they have the leadership to navigate it.