The bug:
It seems as cauldrons don’t emit bubble particles anymore on interactions, unlike older versions of the game. This was covered in an older report (MCPE-134079) but got resolved as incomplete. This behaviour still exists in the legacy console editions, just not Bedrock anymore. Was this removal of that effect in Bedrock even intended or not? No changelog I know of seems to have removed the bubble particle effect off cauldrons from Bedrock.
Steps to repro:
Get a cauldron, a water bucket and a dye
Place a cauldron. It starts empty.
Place water in a cauldron. No bubble particles appear after the cauldron is filled with water.
Use dye on the cauldron. No bubble particles appear.
Expected Results:
Bubble particles will appear on the cauldron just like old versions of Bedrock and legacy console.
Observed Results
Bubble particles don’t appear on the cauldron unlike old versions of Bedrock and legacy console.
Can confirm.