Never thought I'd be using a 4chan thread (or at least an archive of one) as a source, but somehow it was the highest-quality version I could find. Seriously, tracking down the source of this thing was such a pain. Here's what happened:

• I saw this fanart in an old video on Melody's VOD channel.
• I ran it through Google Lens, and it gave me two matches: this Wasoru link and this Buhitter link.
• I went to Buhitter and clicked the original tweet, but it's a protected link now.
• I checked the link on the Wayback Machine, and they thankfully had it archived.
• It's smaller than the 4chan version.

I have no idea where that 4chan user found this in a higher quality than what was on Twitter, but since it's the best version I could find, I basically had no choice but to use a third-party source.

BKaz20 said in comment #2574399:

• I checked the link on the Wayback Machine, and they thankfully had it archived.
• It's smaller than the 4chan version.

I have no idea where that 4chan user found this in a higher quality than what was on Twitter...

Ah, you didn't check thoroughly, @BKaz20! https://pbs.twimg.com/media/FBwVgNCXIAImjGV.jpg by itself isn't guaranteed to give you the highest quality version of an image from Twitter! This is why, when Danbooru fetches the image, it always does .[format]:orig, in order to get the original res. Whenever you're checking Twitter media on the Wayback Machine manually like this, you should always do a full URL search of the direct image link without any file format at the end. Searching https://pbs.twimg.com/media/FBwVgNCXIAImjGV got me https://pbs.twimg.com/media/FBwVgNCXIAImjGV.jpg:large, and asking on the Discord I was told that the image on that link and the one from wasoru are pixel-perfect.