Bing seems to be testing displaying ads on the left side bar of the Bing Search results. Previously, Bing had organic free listing details on that left side bar but now it seems they are testing showing Microsoft Advertising search ads on that panel.

Khushal Bherwani posted an example of this on X, here is that screenshot:

I don’t think I’ve seen ads on that left panel before – but I guess why no put ads there?

This was indeed spotted earlier:

Forum discussion at X.