Bug description
Whenever a root bone is transformed by an animation in a secondary model, the transformation also applies to the same root bone in the main model.
If there are no entities rendered in the world that are using the secondary model, then the issue will not occur, (e.g /kill @e[type=minecraft:chicken], reload resources, and then /summon minecraft:chicken ~ ~ ~ will look fine)
This seems to happen on all entities, but was not present in earlier versions of this mod.

Example resourcepack
bugged-chickens.zip
More model examples can be provided if necessary.

Screenshots
Optifine:

ETF + EMF (Adult chicken is scaled to 2x its normal size):

Version information

• Minecraft Version: 1.20.2
• EMF version: 1.1.0
• ETF version: 4.6.1

fixed for next update

Yes it appears to still occur when swapping them around
Here is a screenshot:

I have been made aware of this in part already

It would help me greatly if you could test 1 thing for me, assuming only 1 of these models is applying this scaling you've mentioned.

If you swap which model is the default and which is the variant (e.g. chicken2.jem) does it still occur?

It might take me several days if not a week to test further myself

I believe this is related to #134

i would agree i'll keep both for now to remind me to use both packs to test