Odd shadow behavior when moving the camera so that shadows are behind hills

I couldn't replicate this through "Normal" camera use, but I know that some people play with really weird camera settings and angles. I took a video of it.

https://cdn.discordapp.com/attachments/955007493510160384/1109589012554977460/2023-05-20_14-08-34.mp4

Start by reviewing the attached video and reproducing the behavior with unusual camera settings and angles, since normal camera use did not trigger it for the reporter. Trace the shadow rendering behavior when shadows fall behind hills, and verify the result across the camera configurations that expose the issue.

Written by the indexing model from the issue text.