Version

lithium-fabric-mc1.21.1-0.13.1.jar

Crash Report File

crash-2024-12-12_20.30.28-server.txt

Additional Information

The server crashed while three players were online with something to do with it being unable to send light packets to the client.

Try updating polymer first. If that doesn't work,
try adding the line mixin.chunk.no_locking=false and the line mixin.chunk.palette=false to the lithium.properties file.