When you have 30 Umbral Shadows, they give you +2 FIDS per allocated bandwith points on your home system. However, this is applying not just to your own home system, but to all sanctuaries on home systems. So if you've got a sanctuary on another faction's home system, the boost applies there too, potentially multiplying the FIDS boost by up to however many other factions are in your game.

Umbral Shadow 30 pop collection effect is, as far as I remember, an empire-wide bonus. So its bonus can be applied to system without Umbral Shadow.

Of course, I think sanctuaries shouldn't be given such bonus.

Here's a save file demonstrating the bug, as well as a couple more bugs. Sanctuary Bugs.sav

The first new bug is that you also get the US 30 pop FIDS bonus on sanctuaries in minor faction home systems. Duyel was a minor faction's home system, and it's also getting the boost. Rath wasn't anyone's home system, and it isn't getting the boost, just to show that the boost is specific to home systems.

The second new bug is something relating to the supremacy victory conditions. If you check the victory conditions screen, you're at 8/8 supremacy and you'll win next turn. You're in an alliance with the Lumeris, Horatio, and Riftborn, with Sanctuaries on the Vodyani and Vaulters home systems; that's 6. Both the United Empire and Cravers home systems are entirely theirs, so I don't understand why you win a supremacy victory.