Oxygen bar refills/freezes when killing fish or lingering just below the water surface

Please note that the relevant part of the attached video starts at 01:30. There is a slight issue with the recording before that timestamp.

Steps to Reproduce:

1. Go underwater in survival mode.

2. Wait for the oxygen bubbles to start depleting.

3. Kill a fish while underwater OR stay very close to the water surface without actually breaking the surface.

Observed Result: When a fish is killed, the oxygen bar stops depleting for a short moment. Additionally, if you stay just below the water surface (without your head fully popping out), the oxygen bar refills instantly as if you were on land.

Expected Result: The oxygen bar should only refill when the player's head fully clears the water surface, and killing mobs should not affect the oxygen depletion rate.