Before I begin I have to admit that I've been running a "subreddit" (Reddit forum) with Eric Barbour, RedditCritiques, which is the running tally of all the dumb crap that goes on within that website. Well, it turns out the 'bots running around the website will "shadowban" comments (i.e., make the comments readable only to the comment maker) just as they shadowban users. Here is a short list of things that have gotten comments blanked by machine or a combination of machine and administrator (the actual employees of Reddit, users can do unpaid moderation; we aren't talking about how mods delete comments for slurs.)
thedonald.win or patriots.win: This is where the denizens of r/The_Donald, the ultra-pro-Trump subreddit went right before the June 2020 "Ban Wave" that zapped it and r/ChapoTrapHouse and 2000 other subreddits off the site. They have made it impossible to have a subreddit for Chapo Trap House (a comedic but highly critical Left-wing podcast) in any form, but the r/DonaldTrump subreddit still exists as a "private" subreddit that is probably moribund. So the Trumpateers made their own freestanding subreddit on thedonald.win (.win being a domain for gambling websites; The_Donald users often used the term "winning") and that switched to patriots.win after Trump lost, but they are still acting like Trump has any say on anything beyond the bulk of Republican members of Congress (he has no Twitter outlet anymore, his blog collapsed in a month). An example of comment blanking of patriots.win:
Aimee Knight, Aimee Challenor: In March of this year, Reddit hired Aimee Knight, the British transgender former Green Party candidate and ex-Liberal Democrat member as an administrator (they had been a mod at r/RPAN, the live video streaming subreddit). American Redditors quickly discovered that their father David Challenor had been convicted in 2016 of raping and torturing a girl while also running Aimee's political campaign. Then it turned out their fiance (now husband) admitted on Twitter to having pedophilc desires (that account was suspended.) Within hours it turned into a free-for-all and comments and people were getting banned for mentioning either name, subreddits went dark in protest, etc. It was all over by April; Knight was no longer an employee. Not even remaining founder Steve Huffman (u/spez) wanted to write the name Aimee Knight in the announcement that the drama was done.
Graham Linehan, "Glinner": Related with the Aimee Knight drama; Graham Linehan, Irish television writer (Father Ted, The IT Crowd) and now anti-trans activist has a Substack "email newsletter" with multiple posts on the Aimee Knight issue. Eric Barbour attempted to post links to two of these articles at r/RedditCritiques and the post was removed, which is from a subreddit he moderates. No reasons were given. On Substack itself Rick Paulas wrote critically about Linehan's British tabloid-style way of discussing/depicting transgendered people, and Ashley Fineberg wrote about Linehan when she started her Substack Trashberg. Below is proof of the Reddit posting.
If you go looking, there are endless demands from Redditors for "Shadowban Word or Phrases Lists" for various subreddits; it's been a major obsession for years judging by the number of responses to this query....if we cut out all the ones about the Trump-era CDC having a "banned words list." Reddit now has user-created scripts like u/RemovedCommentsBot that will confirm if you have been shadowbanned and what comments of yours have been blanked or removed. We have come very far from where the website was at even seven years ago.