Repeat after me: CORRELATION DOES NOT EQUAL CAUSATION.

There are any number of things that could actually be causative factors, here: One would be the economic effect on the birth cohort from around the Spanish Flu epidemic that derives simply from having been born during the time that a huge chunk of the population was eliminated. Have a meteorite hit and do the same damn thing, and you’d probably see similar downstream effects on the kids born during the affected period simply due to things like dislocated supply chains causing problems with pregnant mothers getting enough of the right foods. Some secondary effect of the Spanish Flu epidemic could just as well be responsible for this set of statistical facts as the influenza itself. Using this data to try to extrapolate over into COVID-19 is just irresponsible scare-mongering–Hell, the actual effect of this on the currently fetal could just as well be positive as inimical, with the widespread isolation and lowered stress on the mothers being good for the developing fetus, or the stress of being isolated and afraid due to listening to idiots like this and in the media causing the poor little nascent kiddies to be bathed in a mass of stress hormones while mommy is freaking out.

Just because you can statisticalize some BS does not mean you should, let alone that you should broadcast the ephemeral speculations your dive into the data has produced. If you can draw direct connections, fine… But things like this? Shut the hell up. Looking over how they got these numbers, I see nothing that really indicates a real and identified causative factor, just that kids born during times of stress didn’t do as well as kids who had idyllic fetal and life experiences.