Why is it that some of the labels may say 30 calories but just the proteins calories in the serving size alone outweighs the calories labeled on the serving size?
There is an allowable margin or error with nutrition labels.
Also, less well known, is that not all protein is 4 kcals per gram. Sometimes it’s 3.3, sometimes it’s 4.2. It depends on the food. Marginal differences, but they can add up. It’s always good to double check when you notice something off like that.