Reproduction Steps

Seems to happen after a while of exploring new chunks.

Crash Report File

This is the crash report that mentions lithium:
crash-2020-08-29_18.46.03-server.txt

Additional Information

Note that I've also been experiencing similar crashes that don't mention lithium, here's a report from one of those:
crash-2020-08-29_18.34.00-server.txt

You need to allocate more memory to JVM.

This is not caused by Lithium. Especially with the amount of mods/datapacks you have, 1GB of memory isn’t sufficient.

If you aren’t sure how to allocate more memory, join Jelly’s discord where we can walk you through the process without spamming the tracker. If you don’t have more memory to allocate than 1 GB, I would suggest reducing the amount of mods/datapacks you are running, look into upgrading your hardware, or join Jelly’s discord where we can suggest low-memory JVM options

This is my current run-server.bat:

java -Xmx1G -jar fabric-server-launch.jar nogui

What amount of memory is recommended?

I'll just try 4GB, thanks for your help.