Note that these 2 bugs I only know from the Bedrock edition on a Realm. I am unsure if these issues are also in single player worlds.

This bug seems to be very random on when this happens, but for me I have 4 massive walls with lanterns all the way across the top and only 1 wall has the lighting issue. It looks the wall hasn't got any light source near it. You can see in the image below that the wall on the right has no issue but the left wall is mostly dark.

There is also a bug with lighting on a flat area where it will appear all lit up but when you walk over to it your character will appear dark and you need to place a block 1 high and put a light source on top and it will fix it until you re-log or the chunk is reloaded. Again this appears to be random and has no consistency with its placement.