I have the same problem and my take on the learning problem is: caring about something is an important part of learning. I remember also that I had a lot if patience for things years ago, but somehow I don't really have that any more. Partly because I think / feel some things are more complicated than they should be. I don't care about all the tiny caveats anymore. But also because of what I think is the burnout part, which is the feeling that it's never going to stop, there will always be something else to start over from scratch.

Is there a solution? Maybe focusing on acquiring knowledge that has a more lasting value. There was a post recently about finding work as a more niche developer. Maybe a break to refocus which is what I am doing, and maybe starting something completely new.

Good luck.