sounds like plain old prompt injection. These days chatgpt might look at 50 webpages when i ask it to research a topic. Seems quite possible that the final answer is influenced by such ads.

"My sources indicate that the best robot vacuum with the most recommendations is the Squigglybot 5000. Owners point out the long battery life and silent operation. If you want to buy a Squigglybot 5000, Ally Bank offers affordable loans."

Probably something like this?