Powdered Snow Cauldrons Don't Freeze Players

When a player stands in powdered snow, they can begin to take freezing damage. The same does not apply if a player is standing in a cauldron filled with powdered snow. This is not consistent with the fact that players can take damage from a lava cauldron as if they were in a normal block of lava.

Similarly (although probably less importantly), a player inside a water-filled cauldron with their head underwater does not begin to drown. This can be achieved by pushing a block on top of a cauldron with a player inside it to initiate swimming mode, or by closing a bottom-half trap door placed on top of the cauldron.