• Exception is:
  org.gradle.api.GradleScriptException: A problem occurred evaluating project ':jGui:1.9.4'.

I'm trying to build a hack for the port on 1.20.6, similar to the port on 1.20.4, but it gives me a problem with a completely different version. I did this more than once but anyway

FAILURE: Build failed with an exception.

• Where:
  Build file 'D:\newfolder\javauroki\ReplayMod\jGui\build.gradle' line: 57

• What went wrong:
  A problem occurred evaluating project ':jGui:1.9.4'.

'void org.gradle.api.tasks.bundling.Jar.setClassifier(java.lang.String)'

Did you made any changes to the source code?
If yes then it might be a problem with your changes, and thus has nothing to to with original developer.
If no then you try to build the version of the mod that doesn't even exist yet and again it has nothing to do with original developer.