I think it’s just the utopia image with colors inverted, which is a visual gag that I’m loving

It’s like the evil [character] meme where an image of them was inverted, along with a caption of something that’s the opposite of what they’d say. So, here dystopia is basically depicted as “evil utopia”

it is actually how the exploit was found

The XZ exploit was found because some dude was investigating performance issues in a system, and noticed an unusual amount of time being spent in SSH processing, IIRC.