Mind sharing how old you are? I'm 40 and while this imposter syndrome thing was something I had about many things in my twenties, it dissapeared around my mid-thirties to be honest. It's not that I think I'm the best at those things now. But I can recognize that I am competent in them. Same with BJJ now. When I got promoted a year ago it just felt normal. I was happy ofcourse since it's recognition of my improvements. Same now, I don't expect to be promoted to purple anytime this year, but I can recognize that I'm still improving despite still having major flaws in some aspects.

For me most importantly it's still so fun to recognize that every improvement opens up more possibilities of improving elsewhere, even if it's just a detail. But than sometimes all those details combined unlock some sort of realization and often ability to move a certain way, that I finally get to solve one of my major flaws.