The research shows sharpest declines at 13 years. We have a lot of infrastructure to support young readers. But not the the older readers.
It’s not just screens.
Teenagers are overscheduled compared to years past. My son’s purpose in high school seems to be to build a resume for a future college. OTOH I got into a decent college with mediocre grades and not even trying.
He reads a lot - but it’s assigned reading.
So nerdy, smart kids like my son get taken out of the reading for fun group. Exactly the kinds of kids that would have been reading casually in decades past.