When moving through my world, one that has been constantly updated from 1.13, with the debug screen open, local difficulty changes within the same chunk. At the same time server light level will appear/disappear from the debug screen.

Local difficulty will always be 2.00 // 0.00 when server light is not showing

Local difficulty will be normal for me 3.88 // 0.94 when server light is showing

Edit:

This happens in all areas of my world, not just the area in the pictures.