Recently Facebook has been granted a patent for Shadow Banning technique.
What does Shadow Banning means? It means that the user who has been banned may not know that they are banned but for them everything will appear normal as if they are not banned. They can post, comment or share but it will be visible only for them and not for others when their profile is shadow banned and the user might think everything is going normal until they suspect that their posts and comments are not being reacted upon.
Facebook is not the first platform to bring shadow banning, reddit is known to have such feature. Having such feature as argued might be used for moderation at the same time also can be targeted at individuals who are journalists, activists, advocates, etc., who wants to express their dissent and expose certain truths.
People should know about the existence of Shadow Banning techniques in first place, else they cannot even know they are being isolated or their voice is being suppressed.