Seems pretty cut and dry looking at the complaint.

Allulose is a sugar substitute, considered a sugar by the FDA, and is to be counted in total sugars.

It is also clearly listed in the ingredients list for the ZEROg products. The third ingredient by weight, just behind peanuts for the one I looked up quickly. So it is being added separately from the natural sugars contained in other ingredients.

So definitely an added sugar by basically every definition.

Except the FDA explicitly passed a rule saying allulose didn't have to be labeled as an added sugar because it's not metabolized the same, and only has 1/10th the calories of a real sugar.

https://www.federalregister.gov/documents/2020/10/19/2020-22901/the-declaration-of-allulose-and-calories-from-allulose-on-nutrition-and-supplement-facts-labels#page-66219