Left hand skin customization does not work #13412
Description
Expected behavior
Left hand and right hand should have toggled according to my setting, but nothing happened.
Observed/Actual behavior
No changes
Steps/models to reproduce
MedalTVMinecraft20251221001248134-1766275996.mp4
Plugin and Datapack List
No plugins and no datapacks were installed on the server at the time
Paper version
This server is running Paper version 1.21.11-46-main@8e5e54f (2025-12-20T01:39:32Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.11-39-e5e2c50 (MC: 1.21.11)
Other
The server was running under a velocity proxy, however on older versions of paper you could switch hands with no problems so I doubt it is the proxy especially considering the bug only started occuring after I updated to the current build of paper on the backend server.
The error also occurs on build 39
My modlist has not been changed since before the bug started occuring.