Not sure if this has changed, but the last time I tried the YouTube Premium trial, they heavily pushed their own content (eg Scare PewDiePie) which was so completely opposite from anything I watch on YouTube, I felt I'd just replaced one ad experience with a worse one that I was paying for. I'd rather see the non-stop Masterclass ads (at least they were often relevant) than see PewDiePie everytime I log in.