Bing Search may sometimes show a "Trending in Bing" carousel at the top of the search results. That carousel shows alternative search refinements based on your previous query but it also can contain ads.
Here is an example of it showing an ad card embedded in the other search refinements in the "Trending on Bing" section:
I spotted this via Shameem Adhikarath who posted about this on X:
@Bing is displaying ads in-between news cards on their
— Shameem Adhikarath (@shemiadhikarath) September 27, 2023
SERP.
cc: @rustybrick pic.twitter.com/ZElYXN8O5f
Forum discussion at X.
Note: I used Bing DALL-E for this image, not MidJourney.