my mom is a teacher and she has similar observation. It also has a lot to do with how parents treat their children. i don't know if that's a problem in US, in Ukraine my generation (born late 80s early 90s) is very insecure about their social performance and stats and it's a complete bullshit. The current middle and school kids are affected by that. There is a lot of stuff in children's heads that just needs time to settle and forcing to push through at someone's else pace is counterproductive. it is a regular pattern when a student starts with solid grades but the chase for the highest grade over the years completely wrecks them and their overall grades start to slip hard because their parents conditioned them to perform and they try to brute force their way to high grades like it's a competition when it is anything but. The burnout they go through is brutal. And by the time they finish school - it's just a performer of sorts - a person who is able to do enough for a grade or rewards but there's just no substance no passion behind it. Meanwhile, students who starts off mediocre or low grades at middle school level up significantly by the time they get to high school simply because they commit to figure it out and once they tap into what clicks for them (math, sciences, languages, arts) they just start pieces together their personality jigsaws and it is way less dramatic then with high performers who would do anything for a grade.