Thank you very much, that did help make things a little clearer. I understand it this way now: All vodka is Neutral Spirits, but not all Neutral Spirits is vodka. So even though some of these suppliers make their juice to vodka standards, they for some reason label it as NGS and normally that would require a formula because you are changing class/type.
But that begged the question, why does the TTB not require a formula if you make it from scratch (where I know a lot of people are producing a NGS intermediate, just not classifying it at production I guess?) but require a formula if you cut that first part out? So I did some more investigative digging and eventually remembered a previous reply by @Jedd Haas mentioning the "general-use formulas" https://ttb.gov/rulings/2016-3.pdf. It took a bit to wrap my head around it but what I gathered is, as long as you're making a spirit that fits the S.O.I. of vodka, you don't need a formula.
"TTB approves a general-use formula under §§ 5.26 and 19.348 for vodka produced in accordance with the standards of identity set forth in § 5.22(a)(1) and containing no harmless coloring, flavoring or blending materials other than sugar in an amount not to exceed 2 grams per liter, citric acid in an amount not to exceed 1 gram per liter, or both."
In fact, there is not an option to submit a formula for vodka.