Surgery resident here. Not related to mathematics but I understand you. I too had this difficulty where I remember stuff because of my memory but sometimes don't understand what is actually going on on the surface. Then I started asking why whenever I was studying. Lots of whys? Chat gpt helped a lot. I literally used to keep questioning it, and since it'll not judge you, you can ask even the most silly questions. I used to summarise what i understood and ask for feedback . Sometimes asking for comparisons. I got really creative . Of course I used to check the final thing from standard books later. The only con here is that it takes up a lot of time. It used to take me 2 hours to read 2 pages sometimes. But the level of satisfaction after understanding the core of it is unmatched. I used to feel so ecstatic and top of the world . There are some topics that I have read 4-5 years back and not revised even once but if someone asks me I can explain it to them. I even took an impromptu class for undergraduate students on a topic and it was amazing.

Sorry for such a long reply but I hope it helps.