[2020] Does anyone know why i can lever loot this coffin (end of 4th floor)? Even when i'm on time and i can sacrifice vampyre dust on the fires the coffin is always opened like this. Bug or intentional?

You can only loot 1 coffin per floor until floor 5. This was a safety precaution we put in early in development when the design stated only one treasure encounter per floor.

When we made the hotfix on Friday to enable all of the treasure encounters we forgot about this safety precaution and unfortunately since it's tied to the model of the coffin directly we can't fix it until this Thursday.

Until then you at least now have the option of which one you want to do on earlier floors i.e. do you want to do the prayer one on floor 4 or the magic one etc.