Fix: the 1.20.1 Fabric and Forge builds failed to launch with a MixinInitialisationError (compatibility level JAVA_21 not recognised). They now declare JAVA_17, matching the 1.20.1 Java 17 toolchain. 1.21.x builds are unaffected.
Fix: the 1.20.1 Fabric and Forge builds failed to launch with a MixinInitialisationError (compatibility level JAVA_21 not recognised). They now declare JAVA_17, matching the 1.20.1 Java 17 toolchain. 1.21.x builds are unaffected.