[internaut]

Any interstellar species could be too easily wiped out if the enemy knew the locations of the home worlds, so they would go to enormous lengths to conceal the locations. It is similar to modern war on Earth.

So the flashes in the sky could be enormous depth charges, thrown blind into the abyss to reduce narrow probability counts or ferret out the hidden home worlds.

Since an attack can be total, and come from anywhere, and you can never know if you fully succeeded, the peoples of Glurk-42 had a nervous disposition.

[motoboi]

Have you read Three-Body problem? If you didn't, you'll love that book, for it's depiction of a universe as a "dark forest" full of hunters waiting to someone less cautious to appear is very much like yours.

[internaut]

I have not, it resides mere feet away on my bookshelf and I shall read it this Winter :-)