Default animation controllers are suddenly unhandled in 1.16.100

I have created myself NPCs that use default player animation controllers and they worked fine pre-1.16.100. Suddenly their models became unstable. According to content log GUI, default animation controllers that worked fine before the update, now are "unknown".

How to reproduce:
Create an add-on with a custom mob or NPC that utilizes default player animation controllers.

What is expected to happen:
The entity is successfully created and looks like player.

What is actually happening:
Entities hands and animations are out of place.

Attachments:

• Two screenshots of said error
• Behavior and resource pack files of player-like entities that can be used to check the error.