Seems like that article lacks any useful data. "the very age when, according to publishing lore, lifetime readers are made" Right. I'll just trust lore to be a scientific study.
I'm sure the reasons are an amalgamation of many factors. Covid, screens, educational funding and curriculum, lack of parental care.
Lynn has some good points, and the only reason I was reading at a young age is because my mother took me to the library.
From my own experience, I have to generally agree with Tim. School absolutely killed any interest I had in reading. I was forced to read books I didn't want to read, write book reports for them, and get points marked off because my interpretations weren't the correct interpretations. When I stopped actually reading the books and just rephrased Spark Notes, my grades improved. I found it hard to read for pleasure after having books associated with hard work and pain.
It wasn't until I was in college that I started reading again. I had more control, and could explore books I actually found interesting with my limited free time, and was able to actually enjoy them without having to worry about overanalyzing everything to death. I explored genres based on movies and TV I enjoyed and started to read more widely over time. After reading some blurbs, I also read a number of the classics they try to shove down your throat in school. And many of those I actually enjoyed, without the threat of a grade hanging overhead. I'm sure I missed some greater themes, symbolism, or other small details, and I don't care. Gatsby can kill me with his green light for all I care.