Yes zeta/quark crashes with optifine.
Yes we know this.
Yes we've reported this to optifine.

No this isn't our fault.

Why? Optifine reimplements all forge patches and forgot to add a patch, we Mixin into that method and because of that quark crashes since well optifine replaced that class and it doesn't have the method we need.

There's no way to fix this on our side without breaking compat with other mods or doing silly stuff.

I've already let a person on the optifine staff team know who has forwarded it to sp but chances on a new 1.20.1 version with this fixed are slim.

Good alternatives are embeddium + oculus for forge and check this list for other alternatives for optifine features, https://optifine.alternatives.lambdaurora.dev/

Thanks,
VioletMoon Team

Please do not open more issues about optifine as once again there's nothing we can do.