In response to your comment, I tested Microsoft Edge on my iPad and can confirm that yes, indeed, it does block the ads on youtube.com -- mostly: out of about

In response to your comment, I tested Microsoft Edge on my iPad and can confirm that yes, indeed, it does block the ads on youtube.com -- mostly: out of about 7 videos, an ad was shown to me at the start of one of them, but that is much better than mobile Safari, on which and ad is shown to me at the start of every video I start. Thanks for the tip.