Shokuryou Jinrui is entertaining. It's grotesque and certainly what you would want from a body horror manga. I can't say I saw a huge amount that really shocked me though. It reminded me a lot of Gantz but stupider. If you know anything about biology and evolution then a lot of the backstory is going to seem dumb as a rock

Autistic gripes with the backstory (spoilers):
The aliens require food CONSTANTLY, breed like insects BUT also are incredibly intelligent?? There is no organism that even approximates this in reality and E. O. Wilson demonstrates with the concept of convergence, that if you don't see it on earth it probably wouldn't occur elsewhere (in fact we see the complete opposite on earth, with Life History Theory demonstrating that higher species intelligence is generally associated with slower periods of gestation and reproduction). Organisms are also overwhelmingly dependent on their niche and I can't imagine an organism would ever be able to develop such a voracious appetite that it's whole species wipes out everything else on their planet. Is it meant to be allegory for humanity (would make sense given the continual references to global warming, which has also been greatly sped up by the aliens)? If so it's distinctly poor as humans are already aiming to curtail consumption and aim towards sustainability. Even if you believe the most insane and jabbering of all environmental activists, this would be a questionable piece of allegory.

The aliens are D U M B. Smart enough to invent space travel, but unable to solve their own deep seated biological issues at home?? They are manipulated their bodies specifically so they could get to earth, why didn't they try to solve their reliance of constant consumption and make their own world sustainable??

Prion disease as the solution is... alright? In humans prion disease doesn't manifest in a few years (but maybe if the clones with prion disease are being constantly consumed it would speed this up massively) and it doesn't kill people outright. A few of the regenerators clones developed prion disease due to the high replication rate of their cells(??I honestly have no idea if this is how prion disease naturally develops, but I don't think it is. It's also very rare and is really own seen in instances of cannibalism [the clones would not be eating each other] and very rare disorders.) but would that really be enough to wipe out all those aliens in a few years??

Also... How base and decadent are these aliens? Higher life forms that are about as enlightened as insects. In Gantz the big alien behind the scenes seems genuinely incomprehensible and deeply mechanical/logical in their thinking, to the point where they conjure horror surrounding the technological apocalypse and logic run amok. The big mother alien here is a ball of fleshy nonsense that apparently didn't see any problems with a human that can just endlessly regenerate it's entire body, apart from the head. Prion disease is sort of random, but what about mutations and mutational load more generally? The alien colony would basically be stuck in a situation equivalent to the mouse utopia experiments, which we know don't last forever.