Crash when a player either changes dimension or leaves the server

[SPGesus]

Describe the bug
When a player either changes dimensions or leaves the server, it can cause the entire server to crah in 1.21.1

To Reproduce
Steps to reproduce the behavior:

1. Very rarely, leave the server
2. Sometimes it crashes

Expected behavior

Screenshots

Runtime info (please complete the following information):

• OS: Ubuntu 24
• Minecraft version: 1.21.1
• Mod version: 0.2.0+beta.7.172 devbuild for 1.21.1

Crash reports / logs

https://mclo.gs/sGDF9uu

Other mods

Mod list provided in other log

Checklist

• I am using the official version of the mod.
• I tried the latest development version but the issue persists.
• I searched for similar open issues and could not find an existing bug report on this.

Additional context

[ishland]

Some of your mods is doing thread unsafe stuff causing internal state to corrupt. Find the minimum set of mods reproducible.