I use ad blockers and open source privacy focused software whenever I can but occasionally I have to use computers that don’t belong to me or an older phone where my usual applications aren’t installed and seeing all the advertisements just feels dirty and dystopian.
I think the worst ads are the text to speech ones that say “Download this app today”. The unblinking energenic people saying you can make a living at home are probably a close second.
Paid sponsorships mostly, since sponsorblock can’t do anything without anyone marking a segment as an ad, you will see it in a video eventually.