Flynn effect has stopped during the last few decades. I have been wondering why. What are the environmental things that have happened in the last decades as opp

Flynn effect has stopped during the last few decades. I have been wondering why. What are the environmental things that have happened in the last decades as oppoesd to most of last century? There is only a handful of possible explanations that I have been able to come up: 1. We might want to do more research on the effect of increasing CO2 on cognitive skills. 2. Wealth disparities have been increasing. There seems to be some research on poverty causing decline on cognitive skills. Maybe it is relative, not absolute poverty that does it? 3. We have reached (local?) maximum and are not going to get any more intelligent any time soon. 4. IQ is a flawed measure that comes up with random nonsense. Not so sure which of those I would pick most likely.