Describe the bug
If the body (and only the body, not the entire model) of a player moves, the breasts do not follow.
This is very obvious with third-party emotes like the screenshot below but can also be observed in certain scenarios with just MCA.
Based on this method already looking at the body's pitch, I'm guessing someone already noticed the issue when sneaking, but didn't notice the yaw when punching and didn't think to also consider body roll and pivot for compatibility with third-party mods which modify those.
For a proper fix it might also be necessary to change this scale so it scales relative to the breasts rather than the origin.

To Reproduce
Steps to reproduce the behavior:

1. Enable player model with breasts
2. Press F5 twice to enter selfie mode
3. Repeatedly punch
4. Note how the body rotates while the breasts are fixed in space

or

1. Install MCA and Essential (also available via CF/Modrinth)
2. Enter world and enable player model with breasts
3. Open the Wardrobe from the Pause Menu
4. In the Emotes>Movement category, click the Running emote twice to unlock it
5. Click it twice more to unequip and re-equip it (workaround for an Essential bug where free emotes aren't equipped properly on first unlock)
6. Go back in-game
7. Press and hold R to open emote wheel
8. Click the running emote
9. Observe how the body moves around while the breasts are fixed in space

Screenshots
Using Essential's Sleeping emote:

Version
10.4.7+1.19.3 on Fabric (though presumably the same applies on all versions/platforms)

Latest.log
N/A