Well, we’ve seen one episode out of seven. Based on how he entered the scene in The Mandalorian, I think we’re going to see more of his time with the tribe. So, we don’t know yet that it’s “different for no reason” or “a standalone cosmetic choice.” It absolutely could be just a case of, “This is a group of Tuskens we’re going to spend extended time with, so we’re going to make them visually distinct,” or something genuinely different about them as opposed to the other Tuskens we’ve ever seen. This is, after all, from the same writer/Executive Producer who had people spending a year+ saying, “Whattaya mean, Mandalorians never take their helmets off? We saw 'em do it all the time in Clone Wars and Rebels!” only to verify that…yeah…it’s part of a different belief system among Mandalorians.
My first thought was eggs/direct offcast of some kind of the “sand Goro,” (we really need an official name for that thing 
) and that the pods’ presence doesn’t necessarily mean a Goro will be around. Being a bio-offshoot of the Goro (or some other Tatooine fauna) could account for Vanth’s reaction…or those pods could have been refilled with some vile stuff. Who knows? I don’t expect a show like The Book of Boba Fett to have someone turn to someone else and give us an on-screen explanation of the little details. That’s something that seems more in the purview of a Visual Dictionary (should one be produced for the show); all the show needs us to know is that there are water/liquid pods that can be found in the sand, that they appear to be found in quantities and locations that can be identified if you know what you’re looking for and harvested by hand, but contain a small enough volume that a pod is good for one or a small number of people for a short time and not adequate on their own to sustain a planetary population.
