Light level bug (one time bug)

Idk what happened, i was playing the snapshot, i think it was a one time error, because when i reloaded the save it was notmal, but the light levels changed in a specific area / chunk. i checked to see if it was just a texture glitch by going into debug and cheking the client-light levels, they went from day (~15) to 0 with little to no transition, monsters can spawn in this area and survive in the day. i created another world to test if it happened across different worlds but no result, if you wish to test, the seed is -5701080025195833634 and the coords are -528 346.