So, I wasn't aware that FA favored PNGs and didn't scale them down, so I've updated all of my images (including the one in my scraps) to be bootleg PNGs.
That is to say, they're JPGs that were renamed to PNGs, and that works apparently! So now you can view the images in full resolution here on FA instead of having to go to E621 for that.

(Also thank god for FA's ability to update images after the submission's been published, super useful.)