I want to focus on a particular functional aspect of this: remembering what you've been exposed to.

The best method is rewriting it in your own words by hand. If that seems too daunting then typing is better than nothing but the brain-body connection while moving langauge to script by hand is the real magic.

If you are having trouble remembering what you've been exposed to, and if you want to transform exposure to information into real knowledge, then re-writing it in you own words by hand is the best way to start doing that.

One of the reasons you are not retaining information is because your LLM dependence makes it trivial to apply solutions to problems without understanding either.

Re-learning task independence is going to require effort against friction you are no longer accustomed to. While I agree with many of the other comments here that cutting LLMs out entirely is ideal I also understand addiction and dependence. If you can start writing down what you are learning and using your own notes to answer your questions that may be a helpful starting point for re-establishing your independence and eventually cutting LLMs out of your life entirely.

Secondary suggestion: Read books.