It is for sure this mod causing the crash, as whenever I remove it I do not have this problem.

Here is the crash report:
The game crashed whilst exception ticking world
Error: java.lang.NoSuchFieldError: field_21953 Exit code: -1
Crash log: https://pastebin.com/ftaJqJyq

Whenever I have this mod in my folder, my client crashes immediately after I jump into the nether. While I am in the nether, I cannot reopen my game save until I remove the mod from my mods folder. Afterwards I have no problem.

Also, unrelated, while I have this mod in my mods folder, there is no difference in my overworld save. No slimes will spawn, nor have I ever seen one spawn.

I have tried both the 1.18 and 1.18.2 versions of this mod, neither will work.