I've had some of the x-milk junk and it is as you describe. But apparently has pointed out not all of them are like this. I'm currently assuming, based on the times I've read labels, that the majority and most common are in fact flavored sugar water, but apparently there is some of higher quality available, without sugar added.
ref: https://poal.co/s/insanity/609792/3e53a69d-ee1b-46d2-999e-bb5747b878eb
(post is archived)