YouTube has always been pretty good about their ad policy. I’ve noticed they’ve gotten somewhat sleazier in recent days. You can’t skip ads as much as you used to, and they now have longer “mandatory” (i.e. unskippable) ads.
Could be another indication of trouble at the Googleplex.
I have an add blocker and haven’t seen an add on youtube in a couple years. I have seen warnings stating google doesn’t allow add blockers, which I ignore.