Light bug

I where AFK last night on my realm and when I came back some chunks have a light level of 0.

I where AFK in a gunpowder and string farm to get gunpowder for TNT and I used a trapdoor to stay on the server. When I came back next morning I where kicked from the server.

It was a text that said something like, You Have Been Kicked By A Moderator and when i started playing on the server some chunks that I know worked as they should yesterday had light level 0. I have tried to reload the world and restart the realm.