Ive complained about mobs spawning everywhere bug before, but no one ever gave a sh
I always felt it is related to lighting (Even though it looked ok), and seems like i was right.

While you cant see it with smooth lighting being on,
(Everything looks ok), when its off you can see that some chunks (Random! After loading always different!) are having glitches with lighting.

Probably because my building is complicated (Very big) with approximately 1000 light sources in it, engine is having some troubles with calculations on loading.

My device is Xiaomi Mi5s, 4gb ram

p.s. Not just some areas in the chunks are dark, but everything in the chunks affected (256 height)