This must be like a 1 in a million bug or something because I have never seen it before, but I instamined a dirt block with a torch on it and for some reason the light from the torch that was in a chunk other than the torch didn't update properly

I don't think this is the same bug as MC-172980 because it happened without commands and that bug only happens when placing or removing 64 light sources in a chunk at a time. I experienced mine in survival mode. And looking at the screenshots of that bug it looks nothing like my experience (the lighting is smooth in mine where it sharply cuts off at the borders in MC-172980)