It is exactly as the OP in this thread said - MCPE-154791 Light stays after destroying a torch - Jira (mojang.com). When you place a block in the place that the torch was it gets fixed. Not sure if this matter but there are 2 spawns near (1 is 10 meters away and the 2nd is 13-14 meters away), still I have placed plenty of torches and somehow only one of them got bugged out.
It is exactly as the OP in this thread said - MCPE-154791 Light stays after destroying a torch - Jira (mojang.com). When you place a block in the place that the torch was it gets fixed. Not sure if this matter but there are 2 spawns near (1 is 10 meters away and the 2nd is 13-14 meters away), still I have placed plenty of torches and somehow only one of them got bugged out.