Do we know how much of this decline is US-specific versus a global phenomenon? The article cites no data on that score.

This kind of thing is unfortunately pretty common in American publications, and it drives me up the wall. If you don't compare US statistics to global ones, it's hard to separate out political / local factors from global trends (and to be fair, this is exactly what some journalists want.)

In particular, I'd be interested in statistics from countries with different lockdown policies, as well as those that banned smartphones in school. Beyond US politics, lockdowns and Tiktok seem like the two most likely factors that may influence this.