User keeps seeing their comments, but other users cannot see their posts or their user page. Only Admins can shadowban. Mods can use a tool called automoderator to remove posts by certain users but only in their subreddit.
To add to this, you can also be automatically shadowbanned by spam filters which, at times, can be quite aggressive. I was once shadowbanned for "getting caught up with a spammy IP address" according to a mod.
That happened to some guy and he kept using reddit as normal for three years until he found out. Took it pretty well. His history is painful to look at. Just talking to himself, nobody ever responds or upvotes him.
Was in /r/TIFU recently, too lazy to get the link.
I saw that too. That's what made me check if I was shadowbanned. I'm not nearly as active as he was, but it made me realize I wasn't always just late to the discussion or something.
Minor correction: Posts of shadow banned users are visible, but only after a mod of that subreddit manually approves each one. Basically everything they post is flagged as spam.
That explains a lot. I have a few users whose submissions to my sub are always flagged as spam even though they are fine. They must be shadowbanned.
Interestingly, one of them submits awful content. It's not spam but he is absolutely terrible. I wonder if they shadowban because the algo's figured out you suck.
You can check by trying to visit their user page. If it 404s, they're shadowbanned. The shadowbanning system is terrible. It's not transparent, it just randomly censors people, some of whom happen to be spam, does not notify the people involved and offers no recourse to those who have been shadowbanned. I was shadowbanned a few years ago, I spent about 3 months spamming different reddit contacts, then one day noticed I was unshadowbanned.
