Ignore everyone in here who implies there's even a tiny extent to which this is your fault. It's 100% not your fault. AI is far from the only difficulty your generation has had to deal with in your education. Things like Tiktok/shorts are also damaging. COVID set a ton of students back quite a lot. The school system is fucked in so many ways. And your devices all try to keep you from doing anything "advanced" with them in favor of prepackaged consumer experiences. It's extremely unfair to expect students these days to just grin and bear it and somehow manage to retain their brain function and simultaneously eek out some measure of success in this world. And the trend has been toward the worse.

And yet, your only real option is to do the hard work to reclaim your own brain. But there's good news. First: you're in college. Congrats on that! That's a huge accomplishment in itself! Second: your attention span isn't so broken as to keep you from reading this far. Third: recognizing that there's a problem and asking for help and advice is a hugely good sign that you've got enough level-headedness to improve your situation.

I think a lot of people have already said "stop using generative AI." And I think that's very much on track. I very much think you're right in thinking that AI is probably the biggest source of the problems you're describing. And most of the rest of what people are saying here is good advice. "Excercise it like a muscle." "Engage with communities like this one." Etc.

Honestly, a fair amount of what keeps me avoiding AI is resentment. I don't know if that'll work for you, but keep in mind what they did to you on purpose in service to their bottom line. It's a lot easier to stay away from something if you don't fall for the false sycophancy and you keep in mind the contempt the companies behind it have for you.

Find a hobby that you enjoy that takes a lot of "brains". I write software a ton, but it definitely doesn't have to be that. Yarncraft is surprisingly thinking-intensive. Games like sudoku. Puzzles. Woodworking. Bonus points if it's something that gives you something to "show for it" when you're done.

I'd go a little further, though. It might be good to also eschew as many addictive dopamine sort of things as possible. Tiktok, addictive games, etc. (There's a lot of propaganda from #nofap weirdos out there claiming that porn is the worst thing you can do to your brain. I don't think it's that simple and I do think probably you're the best one to make the call for yourself whether that's the case for you. Maybe "detoxing" from porn for, say, a week at a time could be helpful from time to time, though. Also, I believe strongly that there's nothing wrong specifically with masturbation or (safe) sex itself. (In fact, it's probably better for you to do so than not to do so.) If there's any truth to the #nofap stuff, I think it only applies to porn. And even then, I think that only applies to a minority.)

Consume more long-term educational content. Read books. Watch stuff that teaches you stuff. (I'm really into STEM stuff. Math, physics, engineering, hardware hacking, programming, etc. I also enjoy a lot of social commentary stuff, philosophy, and psychology. But do what works for you.) Opencourseware is a great resource.

Further still, I think meditation is a pretty big "cheat code". It sucks. A lot. For a while. But it gets easier and I think it'll improve your brain quickly in ways you can't necessarily even anticipate now. Start with short sessions. 10 minutes, 5 minutes, or even 2 minutes. Here is a decent guide for beginners. Over time, you'll start enjoying it.

Good luck! You're doing good recognizing the problem and planning to take action to remediate it! And you're more than welcome here. Post updates if you want!