Light appears randomly in dark places

Whenever I enter a dark place, there is a random light in the place when there is no torch or a hole letting any sunshine in.

What I expected to happen was...:
For the place to stay dark as always

What actually happened was...:
Light sometimes appears randomly

Steps to Reproduce:
(this may happen rarely)
1. Dig a big dark place underground
2. put a torch and then destroy it
3. Exit the app and come back to the dark place in a couple of days