for me, setting the plagued attribute to whitelist and adding mob ids (ex: [minecraft:zombie, minecraft:husk]) causes the game to lag intensely and refuse to load worlds.

I am using 1.16.5 and there are no mods that are causing incompatibility issues

scratch that, changing anything in the defaultconfig file makes it refuse to run

Share your config file that refuses to load. It's likely a config syntax error.