I’ve read that it can be a stomach irritant, but I don’t know much detail. Note that ingredients derived from a natural source can be far from the naturally occurring form. Is it “natural” to extract one chemical from a food, concentrate it, and add it to another food?
I think the carrageenan is used to keep milk substitutes from separating. I avoid it, by using canned coconut milk instead of cartons. Canned has very few or no additives. It’s also possible to make your own of any milk substitute.