He was invited to talk about this problem in China in 2016 and got banned after. The Chinese government is allergic to hearing any bad news about how they're running their country and this is fatal if his stats are true.
I used to think that a dictatorship could command their population to do whatever it wants and China would be able to fix this problem by running 24/7 pro birth propaganda and banning contraception/abortions, After seeing their inability to force vaccinate their elderly population and instead deciding to destroy their economy with lockdowns, I'm not so sure anymore.
Or, you know, it could be that some random Christian fundamentalist roadside clowns only contribute to spreading fake news while providing little substance.
What do you think banning contraception and abortions would achieve? It would lead to a proliferation of dangerous underground black markets for these purposes - instead of getting abortions in modern clinics under the supervision of trained personnel, women would go to some filthy basement with an unknown "surgeon" to make this procedure. Or they will abandon these children. "Curing" symptoms instead of the causes never amount to good results - the reason why people don't want to have kids is that it is too expensive under the current circumstances, running some pro-birth ads won't change that. To fix the underlying problem, you have to solve the problems of expensive real estate (in progress already), highly unequal schooling quality (contributes to the previous problem), exam grinding, etc.
Vaccination and zero-covid can go hand in hand because vaccines are not a miraculous "now you cannot get sick" option, especially with Omicron.