In my humble opinion, China grew too fast and their citizens didn’t get a chance to catch up before getting replaced by robots. Check China’s GDP and how it’s now pretty stagnant and will likely continue to drop while being replaced by automation.
Japan was a similar example of their citizens experiencing dramatic growth after WW2, but unlike China, their citizens caught up and their citizens have a healthy GDP.
Add this plus a bursted housing bubble. They have a big problem.