Enviroments in PAYDAY 2 have a value called "Ambient Falloff Scale", it's purpose is, impliedly, to make everything in the map subtly reflect the existing cubemap textures/global cubemap textures of the map in order to make specific materials or areas seem reflective, and help sell the map's lighting and color tone.
However, previously, due to lack of implementation, Ambient Falloff Scale always used a specific, set cubemap texture instead of the current global cubemap, causing high values to reflect a blue-ish sky instead of the intended cubemap, this caused maps like Cursed Kill Room, Hotline Miami day 1 and Watchdogs Holdout to look questionable in nature, and caused some of the lighting to not make any sense, at least to me.
This mod fixed that issue by actually making Ambient Falloff Scale use the global cubemap, which was left as a TODO note inside the post-processor configuration file instead of actually being implemented, at least until OVK fixed it themselves.
Installation: Download the mod and place the "No More Shiny Hellscapes" folder in your mods folder. I don't know why you would do this.