To reproduce:
1. Open attached Unity project "Shaderkasten 2017.1.0f3.zip"
2. Open Scenes --> WaterScene
3. Go into Play mode and observe the water
4. Switch back to Editor mode
5. In the Hierarchy, navigate to DebugObjects --> SceneCam and enable Post Processing Behaviour (Script)
6. Go into Play mode and once again observe the water

Expected result: The water texture should not have changed by adding a default Post Processing profile
Actual result: Colors of the water become flat and unlerped

Note: Enabling Post Processing Script after while in Play mode results in glitchy, flickering texture
Workaround: Exclude WaterDepthTestLayer from SceneCam's Culling Mask and enable WaterCam. Now enable the Post Processing script and go into Play mode. The bug is no longer present, meaning that Post Processing indirectly does not reproduce the bug.

Reproduced on: 5.6.3f1, 2017.1.0p3, 2017.2.0b6, 2017.3.0a2