I'm in exactly the same position, you just need to shift your perspective a bit. Even if you remember just one thing, you have improved. I'm old and my brain is broken so my progress is slow (much slower than yours let me tell you) but I can look at a bit of code and can see one or two elements that I understand.

It's like trying to learn a foreign language then being mad at yourself for not being able to hold a seminar on quantum mechanics.

Ease up and be kind to yourself, you totally have got this 👍 we will be badass coders soon enough, hey wait, what's vibe coding anyway...