MDs get very little instruction on nutrition FWIW, although they would be helpful in terms of longitudinal monitoring.
But perhaps they can refer you to the right person :) In any case, this might depend on the country as well. Where I'm from (Belgium) doctors have been helpful regarding nutrition as well. YMMV though
My wife and I are not vegan, but vegetarian. It sounds like a bad idea to strictly follow a YouTuber without checking in with a nutriologist or doctor when you are full vegan though.
I would still watch her videos though even after this drama. She has some tasty recipes :)