In the new snapshot, bug MC-203748 was fixed, this prevents the player from placing lava in a cauldron underwater. It is now also impossible to place water in a cauldron underwater which logically should not happen. It should either be possible to place water in the cauldron or automatically be waterlogged when its underwater.
MC-275209
It's impossible to put water in a cauldron underwater
Resolved
Fixed
5
Bansed
etanaratsastaja
Confirmed
Platform
Normal
Block states
24w33a
24w34a
Retrieved
In Bedrock Edition, the cauldron is filled with water almost instantly.