16-year-old here. My experience is probably markedly different from most teenagers in the US (I'm an immigrant who goes to a competitive school full of other immigrants) but I find that, for the most part, this article hits the nail on the head. High School is nothing like the usual media portrayal - I've never heard anyone even talk about a party, nobody's doing anything stronger than weed, nobody's fucking or even dating at all.
Smartphone use definitely has a negative effect. I'm in some APs, some Honors, and some regular classes and the #1 difference I've observed between the kids in each cohort is how often they're on their phones. The CP kids leave their phones on their desks and are making out with the damn things whenever they can, sometimes even when the teacher is trying to lecture them. The Honors kids have them under their desks and only use them when they have nothing more pressing to do. The AP kids have them on mute in their backpacks. (I leave mine in my locker, and only use it to listen to music.)
Most of the anxiety is over college admissions - not necessarily to the Ivy League (everyone knows that's just luck of the draw), but the "second-tier" schools (Carnegie-Mellon, Rensselaer, Duke, Cornell, etc.) where over-achieving can still net you a good chance of admission. There's a lot of focus on "building your brand" and trying to "stand out" (make your life more "interesting" in the narrow ways that look good on a college application). The more technically-oriented kids are balls-deep in resume-driven development; they follow the tutorial for every trendy tech buzzword possible (mostly data-science and ML stuff) so that they can blog about it on their Squarespace-generated portfolios. I'm a member of the FIRST Robotics Team and, like everyone else there, I do absolutely nothing, because the team has 5 times more people than it actually needs. I once witnessed the entire programming subteam (about 20 people) spend 3 hours trying to flash an SD card.
The main thing I notice among my peers is an obsessive (borderline autistic) focus on "getting in" and having good credentials. Enjoying your life and doing things that you take pride in are secondary to the all-encompassing drive to impress people who know nothing about you. I wish I could say I'm above it all, but I've certainly internalized it to some extent - I feel a nagging sense of guilt when playing video games, or reading books that don't imply intellectual clout, or anything else that's internally rewarding but "non-bloggable". If I had to characterize my generation with a pathology, it would be exhibitionism.