I definitely feel like part of it is what you listed. Heck I can hardly read linked articles fully and usually just skim them. I have a hard time doing anything

I definitely feel like part of it is what you listed. Heck I can hardly read linked articles fully and usually just skim them. I have a hard time doing anything that won't immediately return value (an issue that's gotten me in trouble elsewhere) and I'm just now crawling out from a bit of burnout. But when I was a kid / teen, it feels like I could learn anything. I could remember how to write in multiple programming languages, a bit of their std lib stuff etc. Now if I'm not working with it at the moment, it leaves my brain. For example I worked on some Node.js a few years ago. Nowadays, I probably couldn't write it to save my life.