Attachable helmets break when using a persona skin

Partner Rank: 2
Verification builds: 1.19.80, 1.20.0

Summary:
Swapping from a classic skin to a persona character in a world with an edited player.entity file, It defaults to a new player model in the mobs.json in the 1.19.80 update.
This change causes the head bone in a custom attachable helmet to no longer follow the head bone of the player
meaning the head moves independently from the helmet and through it.

Impact:
Causes an unfixable visual bug in an unreleased map.
 
Repro steps:

1. Import the attached world
2. Equip a netherite helm and chestplate
3. Select a classic skin and observe the helmet's movement matches that of the head
4. Select a persona character and observe that the helmet no longer moves
5. (optional) Remove the player.entity file from the resource pack and observe that the helmet now works on the persona character

 
Observed Results:
Custom attachable helmet doesn't move when using a persona character.
 
Expected Results:
Custom attachable helmet moves with the head when using a persona character.
 
Screenshots/Videos attached:
Yes
 
Regression builds:
1.19.70

Notes:
The rest of the bones in a different attachment, such as the arms on a chest-plate, work correctly.
Only the head bone seems to be affected.