I recently discovered on a server running version 1.11.2 that during a Zombie Apocalypse Moon in a village I built. Zombies would spawn halfway inside the grass path roads even though the light level around was in the 9-12 range.

I believe this may have been caused by the Grass Path showing Light Level 0 while in F3 mode.

I don't have a screenshot about this since I acted to defend my villagers by killing off the zombies. But it did happen.