Since the 1.16.1 version update on bedrock there have been multi bugs one major one is the increase in lag on both single player and realms, I am not sure as to what is the cause of it but since the 1.16.1 update Mobs have not been working correctly. A few people on single world and realms have notice being hit by random damage with no mobs around, dying to a mob that was not even in view range, and attacking mobs that appear to be invincible and not taking damage... this included passive mobs like the Invincible Llama >.> Reloading Minecraft does help but for a limited amount of time like 30 minutes before it accrues again. Over all what ever is causing this issue is greatly taking from the enjoyment of playing the game.