It means their comments show up as [dead] until they’re vouched by others.

Thanks. I keep [dead] comments turned on and I thought that one was pretty reasonable so I was going to vouch for it but wasn't sure if there was some context I was missing. Your comment provides it.

[dead] by itself is a shadowban. [flagged] [dead] is not.

Note that [dead] itself is not necessarily a shadowban: an unpopular comment will show up like that too. To figure out if the user is shadownbanned you want to go to their profile and check if the account is new or has multiple [dead] but reasonable-looking comments.

Comments can be downvoted to death without being flagged. [dead] by itself does not imply its a shadowban. It's super easy to tell though, because if someone is banned, you can look at their history and see all their posts besides a few that get vouched are dead.

It's really comforting to hear this explained. In the past, when I saw a username with several reasonable comments showing as dead, I was worried it was the work of bots or some conspiracy flagging things unfairly. I'm glad that's not the case.