Ok, so I went to a 90-minute Aurifil lecture today & learned more than I ever thought was possible about thread ... only to realize I still know only a fraction of what there is to know.
First of all, there have been no recent changes in the manufacturing plant. Second of all, it is made in Italy just as it always has been. So we can put to rest any idea that they are now making the thread in some substandard third world warehouse with people who don't know the first thing about dyes (although, let's be honest, that's where most of our fabrics come from & they are still quite lovely ... just wholly toxic to the workers making them, which is why the plants can't exist in the US).
Aurifil thread is actually certified as non-toxic. The process is -- and long has been -- the forefront of thread technology. Almost every part of the process is automated. I remember seeing on Aurifil's website & social media in the past that in years where the previous growing season was a drought, that affected how the cotton took the dye. They only buy top-rated extra long staple Egyptian cotton, but they buy enormous bales of it. Sometimes pickers will manage to sneak in some second-rate cotton in the batch in drought years & it's not practical to catch every time that happens. Aurifil pulls the lower quality cotton if found during spot checks or if someone happens to notice it at just the right time, but it does get through on occasion. If you have a problem with the quality of a batch of Aurifil, they are very good about quickly replacing it & extending excellent customer service (as other members of the board can attest).
Any time you are working with cotton, even if you have the exact same dye lot, there will be variations in the color. I have found Aurifil colors to generally be very consistent. I don't look at dye lot numbers & I've never had issues from one spool to the next, but they aren't exactly identical either.
#2000 is an Indanthren color, which tend to be more consistent than the Reactive colors. The ones that are least consistent are the sand-blasted threads that are variegated single color threads (#'s 3910, 3920, 4150, 4250, 3660, 3840, 3770, 4060, 3320) because the process is considered artistic & no two spools are alike.