Legs enter the player's torso with sneaking while swimming

Summary:
When a player swims on a shift, his legs go slightly into the body.

Steps to Reproduce:

1. Enter the water.
2. Start swimming.
3. Press shift (without stopping to swim).

Observed Results:
The legs will slightly enter the player's torso (not by a couple of pixels, but noticeably!).

Expected Results:
The legs will not go into the player's torso.

Video:
Windows 10:
2021-02-23 22-06-06.mp4

On touch devices:
recording_20210223_222231 .mp4