When standing on farmland, with the F3 overlay enabled the light value does not show. The room is well lit with torches. The coordinates are blacked out because this is on a anarchy server.

How to reproduce:
1: Go underground.
2: Place dirt next to a water source (stationary or flowing)
3: Use a hoe of any type to till the dirt
4: Place a torch near the dirt
5: Press F3