Player model changes if a player sneaks while flying with elytra

The Bug

When sneaking while flying with elytra, the player model changes.

Video

Minecraft 19w39a 2019-10-01 01-28-45_Trim.mp4

Steps to Reproduce

• Obtain elytra and some firework rockets.
• Begin flying in the air using the elytra and switch into third person view.
• Press the sneak key multiple times and as you do this, pay close attention to the model of your player.
• Take note as to whether or not the player model changes client-side if players were to sneak whilst gliding with elytra.

Observed Behavior

The player model changes client-side if players were to sneak whilst gliding with elytra.

Expected Behavior

The player model would not change client-side if players were to sneak whilst gliding with elytra.