They put the autopilot in the wrong mode. The mode they used uses the current altitude, not a default of zero. A good safety check here would be to not record

They put the autopilot in the wrong mode. The mode they used uses the current altitude, not a default of zero. A good safety check here would be to not record an altitude if the plane’s airspeed is moving less than some value (or perhaps better, if AoA is above the critical limit as the wing is stalled).