Does the change correlate with COVID? You might have long COVID brain fog.

Aside from that, this is quite an interesting read as someone with post concussion syndrome. That largely recovered in time.

I've found that going outside, taking a break, and going for a walk helps my symptoms. Lifting weights helps, too, and the modern treatment regimes (not that I followed them; my doctors misled me) emphasise cardiovascular exercise.

Maybe avoid LLMs for a while. They're incredible tools, but I find they encourage intellectual laziness.

Perhaps you have ADHD?