"the mean IQ score on standardised tests for children aged between three months and three years of age hovered around 100, but for children born during the pandemic that number tumbled to 78"

This effect is so ridiculously large, almost 2 standard deviations, that sounds like garbage at face value. Also when one does Ctrl-F in the linked paper one does not find 'IQ' nor the word 'intelligence' besides in the title of a reference....