This has existed for a very long time and I've raised it to DayZ on twitter couple of times but nothing has been done to address it as of yet. The issue happens randomly and not all of the time and it occurs when you leave a server or the server restarts while you're playing. When you rejoin that server or a different server, there is a chance that when you enter that server that the brightness is affected. The appearance of the server appears to be dusk where it looks like it's going to rain. But your vision is also impacted because when you look outward eye level or above, the view adjusts for sun brightness making it even darker. The only way you can really play is by looking slightly down to make the surroundings clear, which is not ideal. The funny part about this bug is that it's specific to the user. In other words, I've asked other players about the weather on their screen and they tell me it's sunny and bright outside. When I close down DayZ and reload the game and rejoin that same server, then it's bright and sunny out for me as well. It's as if the game doesn't reset a setting that controls the outside appearance when you exit. I have documented the problem on this video. (https://youtu.be/npfOZeTuqIE)