The barnard loop is the biggest nebula in the galaxy, but hard to navigate for players, because lots of systems around it extend a sphere or permit locked systems, because the high thargoid presence.
https://map.canonn.tech/route_uia.html Its the big zone of blocked white spheres, and open black spheres.
This zone is know in real life as the Orion Molecular Cloud Complex, and dated from a Supernova that explode 2 Millions years ago:, with Barnard's Loop the biggest of the nebulas.
The interesting part, is that Guardian live nearby, around the Gamma Velorum star (permit locked white zone inside the blue guardian sphere), and that war happen in a similar timeframe of 2Millions years ago.
Lot of start in the zone got displaced by the supernova shockwave, with AE Aurigae, Mu Columbae and 53 Arietis the closest to the explosion, and the ones with the fastest speed, now at 600Ly, 900Ly and 1200Ly from the origin.
We don't know how the guardians won the thargoid war, except form using his own robots, the Constructs. But if the Thargoids have a foothold in the nebula, the supernova could have been the weapon that destroyed their headquarters or home world. And could explain why the constructs, once developed conscience, saw the "nox xenophobic and paranoid" guardian masters a menace to the life in the galaxy.
Now, 2 Million years before, thargoid returned to the SAME systems they once colonized, but because the shockwave, the empire is fragmented and produce small bubbles or presence, the permit locked system.
Exploration of the 3 runaway stars, that lack permit locked spheres, don't show any relevant info. All of them lack planets or moons, and only one have a secondary failed star as companion. Maybe this explain why this stars don't generate his own permit locked sphere, but don't confirm or deny the statment about Supernovas as definitive guardian weapon.
If this superweapon exist, pray that the guardian survivor don't return, and that another Wanna-Be-Salvation scientist discover this weapon.