I don’t have an image to prove it, but I remember google making it a point and bragging of having clearly differentiated ads (in pale yellow I think?).

It was a big contrast and a signal of classy goodwill, back in the age of replicating popups and garish blinking text.

Exactly this. I remember when it was just a couple small links in a yellow banner you could scroll past. Same with YouTube, the ads used to just be a banner under or beside the video but didn't interfere with the main content. Once the ads got invasive, I installed ublock and haven't looked back. I don't feel the slightest bit guilty about that.