That’s 0.005%. Give me a break. Pierre miscalibrated the scale when he was measuring it.
I believe that they are comparing it to other secondary standards, on both sides of the same precision balance beam. The relative weights have changed, and apparently the “primary” standard has drifted away from all the copies, which makes absolutely no sense. Entropy has absolutely nothing to do with it, there isn’t that much entropy in the universe. (At least in the sense of uncontrollable random variations. Procedural errors cannot be rules out.)