Usually means your comments are getting flagged by other users. I’m not going to dig through your comments to speculate on why, but I don’t think there are any automated filters that will kill only some of your comments.
They're instantly pre-flagged upon posting and some others aren't.
This one came pre-flagged.
Probably your account is shadowbanned but people with showdead on are individually vouching for some comments which unbans those comments only.
Instantly when posting them?
The game has changed. Now I can only post a few times per hour and they're automatically flagged. No moderator has given me any contact to explain what I'm being punished for, so I guess I'll be making a new account and hope the same glitch doesn't occur again.