Shades of previous GE90 'rollback' and IFSD from the early days
Only difference was in those cases it was in cruise and was caused by moisture freezing in the P3B and PS3 lines to the FADEC...........solved by increasing the tubing diameters
In both cases, the engine recovered to the proper N1 thrust level as the airplane climbed beyond 400 feet above ground level
Firewalled the T/L's maybe
