that direct link had a concerning title, but then there was this paragraph:

research and meta-analyses over the last two decades suggest that the Flynn effect had already stagnated or begun to reverse. In a meta-analysis examining IQ scores across 31 countries from 1909 to 2013, Pietschnig and Voracek (2015) found that the magnitude of higher IQ scores observed for newer cohorts has declined. Dutton and Lynn (2013) found Finnish IQ scores had differed −2.0 IQ points (0.13 SD) from 1997 to 2009, while French IQ scores differed −3.8 IQ points (0.25 SD) from 1999 to 2009 (Dutton and Lynn, 2015); for these studies, more recent samples had lower IQ scores than previous samples. In a meta-analysis examining nine original studies that observed a reverse Flynn effect, differences ranged between −0.38 IQ points (0.03 SD) and −4.3 IQ points (0.29 SD) per decade (Dutton, van der Linden, and Lynn, 2016). Recent evidence within German-speaking countries, also suggests that the magnitude of higher visual-spatial ability scores in newer cohorts could be declining across certain regions of Europe (Pietschnig and Gittler, 2015).

Linking to a ton of other studies, which is enough data for me to consider acceptable.