Exact same issue. Anything past Forge 34.1.25 gets this error for me.

crash-2020-11-03_14.32.03-fml.txt

Same here, Ice&Fire had this problem, the recently did something to fix the issue.

1.0.5 crashes dedicated server Forge 1.16.3 build 34.1.42

Notes:
ExceptionInInitializerError: null

crash report:
http://paste.ubuntu.com/p/k4NVNZ5v87/

fml server latest:
http://paste.ubuntu.com/p/2qChgn267H/

https://www.curseforge.com/minecraft/mc-mods/unearthed-forge/files/3103900