The TTB regulates everything within wine production, including packaging, with support from other agencies.
Good article: https://www.packaginglaw.com/s...d-level-complexity-0
Currently, alcohol packaging doesnt' require an ingredients list, and I would hazard to guess a part of that is because when, how, and how much of any addition is so strictly regulated that additions fall underneath legal requirements for inclusion. To use the citric acid example, there is a legal limit for how much you can add (don't know it off the top of my head). And, TBH a winemaker wouldn't want to add much of it in any case as citric acid is a potential food source for rogue yeast/bacteria.