The levitation effect doesn't work while entities are inside water

The Bug:

The levitation effect doesn't work while entities are inside water.

Steps to Reproduce:

1. Enter some water and give yourself the levitation effect by using the command provided below.

   /effect give @s minecraft:levitation

2. Wait for a couple of seconds and observe if you levitate.
3. Take note as to whether or not the levitation effect works while entities are inside water.

Observed Behavior:

The levitation effect doesn't work.

Expected Behavior:

The levitation effect would work.

Code Analysis:

Code analysis by [Mod] ampolive can be found in this comment.