"Shadow ban" would be a good term to use for that if it didn't already have a meaning that was different. But it does.
If you use Bing webmaster tools (a logged-in account for the use of the domain owner/content creator) and you can see indications that Bing indexed the content and no indications that errors preventing it from being eligible to show then it is certainly at least closer to a shadow ban than I originally thought.
Still, any reference to a "feed" entirely misses the point unless Bing is the one also serving that feed. I can't see any evidence that Bing displays a feed to the poster.