Ever since I made my first insurgency mission on Al Rayak, I've seen this strange blue line on the horizon that will stay there on certain playthroughs. Usually I can fix it when I rejoin, but rejoining isn't ideal because after getting into a combat support vehicle I do not see the talk to pilot option anymore.
I at first thought the blue line issue was from Al Rayak's strange lighting, but now that I've made an insurgency mission on Clafghan I notice it too occasionally. Not a major issue, but can be annoying as the higher I go in the map the bigger it gets. Here's a screenshot of the blue line.