The ground appears to be flowing under the static objects on a hillside.
- Legacy ID
This is always to able replicate by looking at a rock or static object on a hill and moving along the lower edge of the object.
I tested this in the Alpha and DEV versions
This is caused by wrong texture mapping on the terrain.
you should rename this issue something like "wrong texture mapping with terrain quality on high or above" (low and standard work well)
The glitch only occurs on ground textures, as far as I know, especially noticeable when the polygon is viewed on a low/high angle and therefor most likely, when you get prone.
But there might be a connection with the rendering of clouds (described in this issue #0000567 , since their mapping is messed up as well).
You can temporarily fix it, by setting the terrain quality to low or standard, but I doubt it will take that long to patch, once the devs noticed.