Microsoft is testing using really large images in the Bing Search Copilot ads. I don't believe I've seen such large ads in this ad unit before, so it seems new to me.
This was spotted by Frank Sandtmann who posted about it on LinkedIn and wrote "It seems that Bing is testing the addition of graphical ads within Copilot Search."
Here is the screenshot he posted:
I tried to replicate this, but I was unsuccessful.
Forum discussion at LinkedIn.