Hopefully all my specs needed are listed in the screenshot, but I've been seeing this lighting glitch on random parts of the map. Only at night, where torches are placed, it doesn't register that there is a light source in the chunk it seems (above ground & in caves). Hence, it allows hostile mobs to spawn. I noticed it was doing the same thing in snapshot version 19w09a. (I had to switch off of fullscreen to take the screenshot. I play in fullscreen (1920x1080) and it was still doing such.)