Perhaps it was a civilization that detonated a matter disintegrator that was .65 billion LY radius, and this was the result.
Their calculations for the destruction radius was slightly off by a parsec or two............
There is a theory that intelligent beings develop their scientific knowledge thru roughly the same process, eventually reaching a point where a “scientist” does the equivalent of “I wonder what happens if I try _this_...” and the entire planet/system/galaxy ceases to exist. Maybe someone tried it on a remarkably large scale in the center of that region...