Air temperature rose by 20 deg C to minus 34 deg C for a period of 86 seconds, and the crew switched the engine ice protection system from automatic to manual for around 10 minutes.
Around 22 minutes after flying through the warmer sector the aircraft’s No.2 (inboard left) engine surged and automatically restarted
HazelNuts, while I partially agree with your hypothesis, the report clearly states an air temperature rise, not an indication anomaly.