java.lang.SecurityException: class "net.minecraftforge.fml.common.Mod"'s signer information does not match signer information of other classes in the same package

If what you need is Forge, you can just add it as a dependency from the maven...

repositories {
  maven { url 'https://files.minecraftforge.net/maven' }
}

compileOnly 'net.minecraftforge:forge:1.16.5-36.0.13:universal'

Yea there was an issue when trying to get forge from their maven repo using maven(for the mods that build on this), and this stupid hack kinda accidentally ended up in the release jar. Just put out a 1.0.1 release that removes the Mod file to hopefully fix the random crashes people experience.