Poop cruise!Of course not. It's like Antarctica. You have to take everything with you when you leave. All your garbage and even your bodily waste.
poop bags are probably an upcharge. Just like how they are claiming "shortage" for not giving bags with the expensive sabers now (while still selling them separately in other stores).That's why we haven't seen photos or concept art of bathrooms in the cabins -- there aren't any. Ideally you'd hold it until you're on Batuu and can use a bathroom there, but if not, they will have waste bags available.