My memory is a bit foggy, but I believe it was something like: on a Donald Trump subreddit, a top comment with tons of upvotes was anti-spez. Tons of upvotes meant that tons of people saw it. That comment then changed to saying spez was awesome. No “user edited comment” or “admin edited comment” tag or anything, like what you normally see in edited comments. People banged on spez’s door about it and he admitted that he had both the power and inclination to stealth edit other peoples’ comments.

Since it was a Trump topic, way too many users let what happened slide, but it’s become just one more thing people can point to about Reddit’s issues.