Sky bug: apparently, a known issue.
The screen refreshes in strips of reversed lighting from right to left. This seems to only happen when outdoors is checked. It affects the ground, which is not too obvious, but it's very obvious when it affects the water, as the lighting on the water is clearly reversed mid-screen (and the stripping effect is slow and visible).
Screenshot attached. Spoiler: it's Island One of Archipelago, and specifically, a very amusing
FAIL of mine at the very end of an optimize run. (I thought it'd make for the best capture...)
____________________________
Trickster
Official Hold ProgressClick here to view the secret text
×Beethro and the Secret Society: Postmastered
Beethro's Teacher: In Progress
Complex Complex: In Progress
Devilishly Dangerous Dungeons of Doom: In Progress
Finding the First Truth: Postmastered
Gunthro and the Epic Blunder: In Progress
Halph Has a Bad Day: Mastered (no door)
Journey to Rooted Hold: Postmastered
King Dugan's Dungeon 2.0: Postmastered
Master Locks: Mastered (no door)
Master Locks Expert: Mastered (no door)
Perfect: In Progress (Perfect 8)
Smitemastery 101: Postmastered
Suit Pursuit: In Progress
Tendry's Tale: Mastered (RPG)
The Choice: Postmastered
The City Beneath: Postmastered
Favorite Unofficial Holds (I need to play more!)
Click here to view the secret text
×A Quiet Place: Mastered (no door)
Advanced Concepts: In Progress
Archipelago: In Progress (Island 12)
Break Out Of Jail: Conquered (86%)
Dr. E. Will's Mega Complex: In Progress
Hold Anonymous: In Progress
Paycheck: Conquered (75%)
The Test of Mind: Mastered (RPG)
Unfriendly Islands: In Progress
Val Unrich: In Progress
war10: Mastered (no door)
war15: Mastered (no door)
war: the truth within: Mastered (no door)
Washed Ashore: Mastered (RPG)
My HoldsClick here to view the secret text
×The Plague Within (RPG) (alpha)
Tinytall Tower (Smitemaster) (beta)
Do Not Disturb Compilation (level contributions) (in review)
Riddle of the Bar (compilation)