Resolution: Awaiting Response
Affects Version/s: Minecraft 18w43b, Minecraft 18w43c, Minecraft 18w44a
Fix Version/s: None
When a block on fire is broken, the light of the destroyed fire is not updated.
Put a tree on fire and wait for the destruction of the blocks and you will observe the not updating of the brightness level (also affects the menu F3).
From Philipp Provenzano:
This is partially resolved in 18w44a (iirc already 18w43c).
Lighting is now correct clientside. However according to F3 it's still wrong serverside.
Relogging fixes the serverside part. However, at least for spawn chunks, teleporting away and returning won't fix the issue and the wrong lighting is then actually synced to the client.