AI slop is the output of all generative AI, full stop.
Slop itself is anything produced for the sake of being produced. Something without feeling or soul, just more content for the content machine.
Like, yes it does take some level of skill to "prompt engineer" the AI and get it to show you the thing you want, but it's still not a distinctive style, it's still not your style. If you say, "sloth astronaut" I can imagine that in my head in my own way, there's no value in producing an AI image. As far as I'm concerned, an AI image narrows down all the possibilities of my own imagination into the specific piece of slop from the slop machine. If I wanted to see it, the point would be to see an interpretation in someone's style.
I can't remember where I saw this argument recently, it was something coming out of Capcom saying they'd use AI for background details and people citing specific examples from Pragmata maybe? Things like vending machines and environmental details that could be streamlined with the help of AI. But even these small details are places for environmental artists to shine. Show off their skills, hide small details and world building, and little in jokes. It may not be much but it adds to the overall texture and flavor of the product. It does matter.
AI is slop, is slop, is slop. There's absolutely no reforming it and if I detect even a whiff of it, I'm out.