I think leetcode is just like anything else you practice - in order to actually improve you need to practice the right way (or in the OP's case, with the right state of mind! Being burnt out is a fundamental problem which needs to be fixed first!)

I started out thinking I was pretty smart but got blasted by a fairly simple question on my first screening interview. I started looking at random leetcode questions but that didn't really work - I soon figured out that I needed to learn the concepts one at a time. I think that is the way to do it, get a list of general topics, learn about it, then practice just those questions until it clicks.