The show “mayday” ( flying on empty ) has a good reenactment of the flight.
FYI: Airbus changed its fuel check policy after this , IIRC, to ensure fuel checks were done every 30 minutes ( used to be much longer before ) Max and Airbus manuals ( emergency/abnormal checklists ...” fuel imbalance“ )updated to emphasize to check for fuel leaks before opening cross feed to balance fuel to prevent the same problem.
Not sure about the A330 but the narrow body Airbus triggers a cockpit “caution” when the fuel imbalance reaches 1500 KGS.
Various places a fuel leak can come from and , actually, a leak from an engine is the best one if caught early because you can totally stop it by shutting down an engine ( o.k over ocean, not great if over high mountains but A330 has enough power one engine to remain over it versus narrow body Airbus ).
High fuel flow ( and low N1 ) are early indicators of a possible fuel leak if one is suspected.