https://i.imgur.com/lRWT6wS.gifv
https://i.imgur.com/BuEa97v.gifv
The image speak for themselves, it's not taking the crouching state from the correct client, only the viewer.

I cannot reproduce it. Are you using the latest version?

When the viewing player is in 3rd person, for some reason the crouching syncs up with their model and not the other player's models with themselves.
This happens not to hard position parts but physics parts.
Attempt this with physics parts.

I'm unsure if it's a mod conflict, I should test more.

https://i.imgur.com/vODerLa.gifv
https://i.imgur.com/OIu1TDY.gifv
I'm testing this out in LAN.
Mods:
[✔️] cpm-1.0.3-beta
[✔️] data-loader-1.1.0+mc1.14.4
[✔️] DiUI-1.0.4.1
[✔️] fabric-api-0.3.3+build.234-1.14
[✔️] fabric-language-kotlin-1.3.40+build.1
[✔️] GamemodeOverhaul-1.0.1.1
[✔️] i-am-very-smart-1.5.0+mc1.14.4
[✔️] level-up-hp-4.4.0+mc1.14.4
[✔️] malilib-fabric-1.14.4-0.10.0-dev.20
[✔️] modmenu-1.7.10+build.119
[✔️] nomoreglowingpots-1.14-1.0.0
[✔️] torohealth-1.14.4-fabric-3
These are all the mods I'm using to test models.

"I cannot reproduce it. Are you using the latest version?"
Also, yeah, I'm using the latest version.