I've noticed the brightness effect as well, but only on my LCD monitor. My other one is darker so I actually like the extra brightness.
It is not just increased brightness

its a whole new texture which appears everywhere. So, if far away you saw grass and you walk closer, you don't see it anymore^^
A bug and so the lightness.
btw. Hydlaa is full of objects which aren't affected by light, or something. Like the Laanx statue is always same as bright and road in some places completly black. There are many more lightness bugs in the new .017 release, than there was before.