On 2020, a Boeing 737-800 flight crew identified significant discrepancies when comparing their Operational Flight Plan weights and passengers by category with those on the Loadsheet presented. After examining them and concluding that the differences were plausible based on past experience, the loadsheet figures were used for takeoff performance purposes with no adverse consequences detected. It was found that a system-wide IT upgrade issue had led to the generation of incorrect loadsheets and that ineffective communication and an initially ineffective response within the operator had delayed effective risk resolution although without any known flight safety-related consequences.