Using the latest version of Geckolib 4.2.3 causes the mod to stop the game from loading since it requires Geckolib version exactly 4.2.1 ... as a quick fix for the server I edited the mod's fabric.mod.json file where "geckolib":"4.2.1" to now read "geckolib":">=4.2.1"
With this fix the game loads and the plushies seem to work fine.

Minecraft 1.20.1
Fabric 0.14.22 / Api 0.90.0
Perfect Plushies 1.3.0

Updating your Perfect Plushies version should fix that since we fixed that in a newer version.