> All dane-pgp's proposed law would change is that when they change the labels to match the new formulation, which they
must do, they would have to include a change date or a version number of something like that on the new label.
The proposal was a lot more aggressive than that -- dane-pgp specified that the packaging must mention if the ingredients stay the same but their relative proportions change. Under current law, there is no reason to alter the labeling for such a change[1], so you'd be seeing a huge requirement for new labels that weren't formerly required.
[1] Actually, there are two. First, you might switch up the relative proportions so much that the rank order of the absolute amounts changes, which would require reprinting the ingredients list. This is really unlikely.
Second, you might end up altering the Nutrition Facts information. That would also require relabeling. I don't know how likely that is; the Nutrition Facts panel is a pretty low-resolution instrument.