It kind of depends on how you define “flyaway.”   Transient magnetic disturbances can cause loss of communication and induce heading errors, both can trigger your drones failsafe. How you have your failsafe set will determine whether the drone “fly’s away.”   If it entered failsafe because of an issue with GPS and failsafe is set to RTH then it doesn’t know where home is and just flys in an arbitrary direction.  You think it’s flying away, it thinks it headed home and your both wrong..