Exactly as the title says, when loading MouseTweaks on 1.20.6 Lunar Client the game immediately crashes.

Can you post the game log?

Hello,
I do have the same issue with lunar client and MouseTweaks.
Here is the pastebin of the logs from the lunar client for the game launch.
To give a bit more of context, you can load a bunch of other mods, but MouseTweaks is causing the game to crash on start.

Versions

Minecraft: 1.21
Mod loader: Fabric 0.15.11
MouseTweaks: 2.26

That client has its own obfuscation, and its mixin remapping that it has to do due to this, fails on Mouse Tweaks for some reason. I don't think I can do anything with it myself, Lunar devs will have to take a look.

I'm gonna check with them if they have any idea. 👍

Did you find a fix for this?

Has anybody found a fix yet?

Susser, the owner of mouse tweaks said that it's lunar clients problem that mouse tweaks isn't working so there isn't a "fix". Lunar client has to fix the problem themselves.