Breath meter still goes down while paused in Singleplayer

In a singleplayer world, the player’s breath meter goes down, even though no game activity should be happening while the game is paused.

How to reproduce:

1. Build a column of water tall enough so that the player can be submerged in it.

2. Submerge yourself into the water, have some of your breath meter go down, and then pause the game.

3. Wait a few seconds while paused, and then unpause. After unpausing, you should see that your breath meter went down.

   1. Note: It’s also possible to start taking drowning damage, however you will only be dealt one tick of it.

Expected result:
The player’s breath meter should stay the same in the time between pausing and unpausing.

Actual result:
The player’s breath meter goes down during the time between pausing and unpausing.