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.
