Cubes of stars like this are fairly common in-game because of how the galaxy is generated. The problem is that as the star density increases towards the core, the B-class stars also get denser, and can be seen from quite a distance away. These stars are generated in 160LY cubes, so if the difference in density between adjacent cubes is large, the border is very visible.
The brighter stars are generated in bigger cubes, but are sufficiently low density that the borders are never that obvious - while the dimmer stars are generated in smaller cubes but can't be seen from as great a distance so the edges generally can't be seen from far enough away to make them obvious.
Fixing it would involve completely starting over with the galaxy generation, which isn't practical now. They could in theory work around it by adjusting the draw distance for B-class stars, but then lots of familiar constellations would look wrong or disappear when in Sol.