But most of the channels I'm interested in have "in video" ads (ads put there by the creator rather than Youtube, I don't know the industry terminology) that remain even if you pay for Youtube Premium.
I wish Premium provided some way for me to predict how many of these kinds of ads are in a video I am considering watching (e.g., by requiring the creator to tell YT how many there are and imposing consequences on creators that lie) but YT does not.