Calling it now. It's a dust cloud.
Yeah, it was more gradual than just turning off. But you have to wonder at the size of an artifact that would block out a massive black hole.
I hope it's only dust move past and not some huge, alien death machine blotting things out.
Black holes emit radiation, but I believe in this case is simply the rapid decrease in visible light is the mystery.
7-8 months from "normal" to dimmed enough to comment on it is pretty quick on a galactic timescale. I can't imaging something smashing an accretion disk or blocking it in that short a time that wouldn't have raised it's own red flags.
Cool. Eclipse of the black hole by who knows what.