EXCERPT
Shadow banning, also called stealth banning, hellbanning, ghost banning, and comment ghosting, is the practice of blocking or partially blocking a user or the user's content from some areas of an online community in such a way that the ban is not readily apparent to the user, regardless of whether the action is taken by an individual or an algorithm. For example, shadow-banned comments posted to a blog or media website would be visible to the sender, but not to other users accessing the site.
The phrase "shadow banning" has a colloquial history and has undergone some usage evolution. It originally applied to a deceptive sort of account suspension on web forums, where a person would appear to be able to post while actually having all of their content hidden from other users. More recently, the term has come to apply to alternative measures, particularly visibility measures like delisting and downranking.
Source:
https://en.wikipedia.org/wiki/Shadow_banning