Dual input
Approximately two minutes after the autopilot disconnected, the aircraft had climbed several hundred feet.
Most experienced Airbus pilots are aware of this design trait.
According to the NTSB report, there were 'dual inputs' i.e. both pilots ‘pushing or pulling’ the sidestick at the same time. Dual inputs are algebraically added which results in double the input, or a very severe rate of change if the push or pull is in the same direction.
Leave you with it.