We had a little over 1500 kg uplift discrepancy listed on the fuel sheet the other day. The refueler was asked to investigate and came back with a new fuel sheet stating that the discrepancy was now around 800 kg which was within our limits based on the uplift quantity.
The reason given to me through a third party was that the fuel temperature check of the bowser had been done 4 hours earlier and when a new updated temperature was used, there was a new and supposedly more accurate fuel uplift quantity.