Can't open the game with ModMenu mod.
Error: The game crashed whilst initializing game
Error: java.lang.RuntimeException: Could not execute entrypoint stage 'client' due to errors, provided by 'modmenu'!
(Deleted all mods and stayed only Modmenu and your plugin)

Mods, I use:

I think this is because the ModMenu version you are using is out of date. I would recommend updating to the latest one and seeing if it still works. I think the latest version can be found on the TerraformersMC maven repo, and you can find a jar for ModMenu v1.16.8, which works with 1.16.5, or v2.0.0-snapshot, which works with 1.17 snapshots.