spawnpoint is broken

I am playing on a survival realm and everytime I am lost in a cave or wherever I am lost, I kill myself to get back home. I have always done this in any world and this bug has never happened. This might not actually be a bug because there are some hackers or griefers that might be in my realm breaking my bed. But i set my spawnpoint using a bed and then when i respawn, i spawn back at the world spawn, not at the spawnpoint i set using my bed.