Since I have 1.8.0 of the mod, I always have to delete the "infinity" folder from [world]/datapacks. It seems that if the content is re-generated on load, it's fine - but launching a world with this data will result in mentioned error message.

Minecraft 1.20.1 - Java - 4G RAM assigned to client - Endeavour OS (Linux distro)

For now I have reverted back to 1.7.2 which did not exhibit this behavior.

Try deleting both datapacks/infinity and config/infinity, this should fix the issue.