I decided to compare Ads UIs between DDG, Bing and Google. Setup: Chrome incognito, Mac Query: "slack" Results: https://imgur.com/a/oi6rEZy

Summary: - For all 3 of them, Ads look just like Search results - DDG and Google have slightly more noticeable Ad badge than Bing - All 3 of them had exactly one ad (from Slack) at the top - All 3 of them have slack.com as the top Search result

I repeated my test with a few other queries ("basecamp", "sonos", "credit karma", "robinhood") and the observations were generally the same: ads on top, indistinguishable from the Search results, followed by the expected result at the first position in Search results.

Disclaimer: Hold a lot of GOOG!