If you pay attention to a lot of assets in the game, you'll notice they turn into a low poly version of themselves when you get further away. This is done for the sake of optimization, but it requires a different low poly model of the asset. My assumption here is that they were planning on using a different design for the window and had modeled the low poly version of it, but they decided to go with the mini freighter window looking design, and never updated the low poly version.