The problem with shadow banning is the lack of notification regarding rule breakage as well as some harmful psychological effects. People who are shadow banned

The problem with shadow banning is the lack of notification regarding rule breakage as well as some harmful psychological effects. People who are shadow banned may not realize they did something wrong / against the rules so they may continue saying the same types of things, without getting flagged / downvoted, thinking maybe it's okay. When they find out they were shadow banned it's easy to feel like an idiot especially if the site allows you to review what they posted while shadow banned. I know reddit has taken the stance lately to only use it against spam accounts as it's highly effective against those.