I think I was around lv 20ish when there were a bunch of kanji that started getting mixed up in my head. One of my greatest tools to help me was a plugin for visually similar kanji. There were a lot of times I mixed up kanji like 湯、場、and 揚 for example. Having all the similar kanji lined up to compare helped me differentiate, and if I was mixing it up with a kanji that wasn’t showing up then I could add it myself! There’s also a plugin called confusionguesser that guesses what you might have been thinking of when you get a problem wrong, and I found that really useful for helping me tell apart similar vocabulary (I’m not sure if you’ve gotten to it yet, but 栄光 and 光栄 constantly find their way back into my leech pile)
Hope those help!