My mom thinks any URL with a padlock next to it is über secure [0][1] and that she can give her bank details without worry.
[0] https://zeltser.com/padlock-and-favicon-confusion-in-browser...
[1] https://support.cloudflare.com/hc/en-us/articles/200170416-W...
https://blog.chromium.org/2018/05/evolving-chromes-security-...
Replacing "Ad" with advertiser's icon is simply a method how not to display "Ad". I expect that many icons will not be company logos, but rather something that seems like it would normally appear in a web page: a small arrow, a tiny dot, a thumb-up, etc.
Then the Google will have credible deniability: hey, we didn't make the icon, the advertiser did, blame him. But of course they are the ones who refuses to display "Advertising" clearly.