[curiousfiddler]

I hear you. And there is good advise in the comments, but one thing I'd think you should also explore is your emotional response when you hit the harder parts of a problem. Sometimes, it is not the lack of knowledge or understanding of a subject, but the emotional response (subtle anxiety, anger, stress etc) that hinders progress when you hit an uncomfortable stage in problem solving. To add to it, leetcode and interviews have the added pressure of time limitations.

Observe your emotions - there may be a completely different solution to your problems.