For everyone as confused as me:
Per reddit poster singtc:
Answer: Alright so what's actually going on in r/comics beyond what Yuri is, is that a popular creator u/MuyHiram has surpassed the subreddit number 1 upvoted creator u/pizzacake. u/MuyHiram's main gimmick is making cute webcomics usually about lesbians (or Yuri). This lead to u/pizzacake joking about it with a comic making the joke that the way now to get upvotes in r/comics is by making Yuri comics, and other prominent and less prominent creators have joined in on the joke as well. In the comics you sent it actually explains in the comments what the "Yuri wars event" is. this is how I know... I just scrolled down to the comments.