Lying flat is a symptom, as is for profit tutoring and the Chinese government banning it. The root cause is the culture [1] [2] and socioeconomic conditions [3] [4].

[1] https://en.wikipedia.org/wiki/996_working_hour_system

[2] https://www.emerald.com/insight/content/doi/10.1108/RAMJ-03-...

[3] https://www.bloomberg.com/news/articles/2021-05-17/china-s-h...

[4] https://www.reuters.com/world/china/cost-having-child-china-...