This particular vanilla lighting setup always looked kind of poopy to me, mainly because of how aggressive the shadows were. The most obvious change is the sky. Also some subtle tweaks to the sun and ambient light brightness.

Not sure how many heists are affected, but Bank Heist, Watch Dogs, Jewelry Store, Diamond Store, Transport Park and Downtown are among the ones that use it.

This mod requires BeardLib.
Extract zip to mod_overrides.