Now now, we all know vacuum stabilization events travel out from their sources at the speed of light, if it were to happen it would be against the laws of physics to see it coming.
More interesting is one of the actual proposed explanations. A massive spinning magnetron gradually slowing down until centrifugal force can't keep it from collapsing into a black hole anymore. And when the source of the magnetic field suddenly gets cut off from the outside universe by being engulfed by the event horizon, the magnetic field has no where to go but... out. The most powerful magnetic field in the universe getting converted almost instantly to energy; creating a spark that lasts seconds and outputs more energy than the sun has in the past million years.