For context there are many theories for why younger generations are less “cognitively capable” than older generations. Nowadays we call it the reverse Flynn effect. IMO this article is nitpicking, probably confirmation bias at play.
But for example, in Denmark, when plotting measured IQ against first name, we observe that there is cultural effect, that would explain that the "reverse Flynn effect" is simply an averaging down, caused by the import of migrants from lower IQ regions. The "reverse Flynn effect" is not observed in Singapore, for example, which has maintained consistent high IQ over many years.
https://emilkirkegaard.dk/en/2019/06/article-out-first-names...