This is a story I read in the past couple years. It was too long to just be a short story in a collection, but I don't remember it having cover art or anything.
It centers around an AI dreadnought that failed to save the Earth from aliens. Its crew all died in the last battle before Earth was destroyed. The dreadnought has spent thousands of years making guerrilla raids on the aliens' territories, with pauses to repair & improve itself.
The aliens are an expansionist multi-racial federation, with semi-religious veneration of the "leader" race, kind of like Halo's Covenant or Warhammer 40k's Tau. There are still some humans around because the aliens initially missed a colony and found it later; the humans don't know the aliens were responsible for the destruction of Earth and are now an (oppressed?) minor member of the alien federation. Only the top echelons of the alien federation know about the ship because they cover up all its attacks for propaganda reasons; the leaders hate the ship and call it the Wound.
The story is a mix of naval combat as the aliens try to kill the ship, flashbacks to the past, and a longish section where an alien ship with some human crew finds & boards the dreadnought, thinking to salvage it because nobody on the ship is a high enough rank to know about the Wound.