Mods used:
Version 1.20.1
Forge loader version 47.3.10
Alex's Caves 1.1.5
Citadel 2.6.0

This visual bug only happens for the person who cast the bubble effect. (Meaning the visual works just fine when a deep one is responsible for it)

If it is player-casted however, the bubble's visual stays past the cooldown of the effect (Mobs not drowning anymore but bubble is still shown around them)