I haven't used Google in years, so I have no idea what they are doing these days. In fact, the other day when I saw that Berkshire bought 4b in Google stock, that was the first time I even read anything about them in years.
But yeah, if their AI only summarizes the first page, and most of the first page is ads (and I'm sure the other 2-3 pages shown have been SEOed within an inch of their life anyway) then that would lead to questionable results.
The DuckDuckGo AI results are from a heavily anonymized ChatGPT so they aren't based on any displayed results, just on the typical chatGPT results, which is probably mroe of a regurgitation of Reddit and Wikipedia.
I use Brave pretty much exclusively at home and I have been starting to play around with the LEO AI that they have built in. It is interesting, but still not something I am willing to dive into head first!