It's a reference to an infamous 4 panel comic strip called "loss". It's one of them ancient memes from 2008. If I remember correctly, the story of the comic is that the dude rushes in to the hospital to find his pregnant wife had just lost their baby or something. If you dumb it down enough and reduce the characters to lines, you end up with
Apparently Sopuli/Lemmy/Firefox g-thumb on Linux automatically flips and rotates images using exif data which is stripped when posting to what it thinks is the right side up. How annoying.
Lemmy strips EXIF data from pictures, which would undo your rotation if not done "for real". (That is done by default because EXIF data could be used to identify users)
Try saving a copy of the rotated image and upload that one? Might help, but that depends on the app you are using.
Might be a misinformed take, but I always saw these as making fun of the original/the artist, not enshrining it. The webcomic as a whole was so-so and fairly innocuous at the time, but Loss represented such an incredibly cruel and tone-deaf shift that it legitimately upset/bewildered a lot of people.
I couldn't say with confidence why people continue to reference it, but maybe helpful as context?