I've recently been searching for some how-to videos and the number of ads is insane - but somehow they don't show when I watch in the video search results in DuckDuckGo
Same here, not using YouTube's built in search function eliminates most of the ad and also recommendations problems. I use You.com since they additionally show Reddit and TikTok results which I sometimes find more useful than YT videos.
I'm pretty sure YouTube doesn't play ads in embeds (as much?)