If a Cauldron is filled with water and it’s mined, the water disappears. I came up with a solution that if a Cauldron is filled with water and it’s mined, it would drop water. However, the Cauldron has different stages of it being filled so that would affect how much water would drop. Here are some examples:
Cauldron Completely Full: Drops a complete water source block that will stay there until being blocked or absorbed.
Cauldron Almost Full: Drops a big source of water but will slowly go away.
Cauldron Half Way Full: Drops a smaller water source and will slowly go away.
Cauldron is Barely Full: Drops a tiny amount of water then immediately disappears upon impact.
This should also have the same effects for when a Cauldron is filled with potions and lava.