Summary: the player character is apparently walking on a translucent ramp while going uphill.
Taken from Single Player, Sinner’s Refuge at the waning portion of the night. This is dependent on moonlight, and time of day. There is apparent airspace between myself and my shadow, as well as elements in the room and dead NPCs (to the right of my character in the upper pic).
Second (bottom) image is as the moon is moving and my toon is stationary.