Last week, Bing had an unusual bug, a bug with its cache page results. The Bing cache was showing not just the cache page they had of your site, but also showed content from non-related sites below or above your page.
Bing fixed the issue about 24-hours after it was reported to them and said it was a bug, not a hack. Here is Bing confirming the issue:
Thanks for reporting. We're aware of the issue that caused occasionally Bing cache page to display content from other pages. We are on top of it and rolling out a fix. Bing search Index and results are not impacted by this issue.
— Bing Webmaster Team (@BingWMC) November 8, 2019
Here is a screen shot of what my Bing cache result looked like that day, notice the content on the footer:
This is all resolved now but Bing really didn't say what the issue was. It was not a "hack" they told me, but rather just a "bug."
Forum discussion at Twitter.
