I stopped playing after Stormblood release and once I completed the main story quest. I'm playing again for two weeks now and lag is really awful. It's horrible. And of course, first, I checked it wasnt my ISP.
I'm from France on Louisoix (so Chaos data center too)
Most of the time it's people I'm running instances with who "teleport" themselves a few yalms away, or crafting that is nearly impossible to do as sometimes all the skills are just slow to use and then fail without reason (and it's not just RNG here).
I hope that SE will do something !