The bug
A painting shown inside a spawner is dark.
Note: It appears it is world generation or position dependent whether the painting will appear dark. However, in superflat worlds at spawn this issue can be reproduced consistently.
Reproduction steps
Create a new "The Void" superflat world
At spawn, use the following command
/setblock ~ ~ ~ spawner{SpawnData:{id:"minecraft:painting"},Delay:32767s}
❌ The painting appears dark
Side note: When teleporting multiple thousand blocks away from spawn (e.g. using /teleport ~ ~ ~10000
) and using the /setblock
command from step 2 above again, the painting is for whatever reason not dark.
Fixed for 1.9