I’m skeptical that there’s a filter like this over the whole game. If you look at the all of the leaked screenshots together none of the others are anywhere close to this dreary to my eye. Although some of the other images have different issues like extreme darkness/low gamma which makes me think some of them were never intended for the public. They have also since been pulled from the site (supposedly this was the original location). Maybe it was a look they were testing at some point and then scrapped, who knows.