Alright, so here's what went down for sure as best as I can gather:

Recently there's been a influx of new users who've joined reddit. The Majority of them interested in memes flooded into r/memes as reddit has them listed as one of their default 'meme' subreddits.

Many of them had been flooding over to the sub r/dankmemes, where they brought practices such as reposting and 'facebook style memes' over to their sub, which the sub isn't at all fond of. As of 8 days ago the sub put in rules to keep members from the r/memes community from posting content on r/dankmemes.

this message sent by the founder of r/memes to the user who announced the posting ban shows that the head of the sub wasn't exactly happy about r/dankmeme's decision, assuming at least that the message wasn't a joke or satire.

Between r/dankmemes decision and r/memes response (which got turned into a copypasta that the automod message used as a base), this has created a fair amount of tension between the two groups. the allegations in that automod message are certainly interesting though, as that could mean this move is mostly or entirely unrelated to r/dankmemes, or at the very least unrelated to their decision to ban members of r/memes from posting on their sub.

Regardless, for one of the above reasons or some other reason, a user who was a mod of both r/memes and r/dankmemes decided to sabotage the r/memes subreddit, messing with all sorts of things, editing the automod with what OP posted, erasing the wiki, and replacing the styling of r/memes with the styling from r/ABraveJerk , another sub the rogue mod is also a moderator of.

And That's all that's happened so far, The rogue mod was removed from r/memes and the sub is now trying to do damage control. Hard to say for sure what's going to happen next.