When building the 1.18/main branch I get:
java.lang.UnsupportedClassVersionError: net/fabricmc/loom/bootstrap/LoomGradlePluginBootstrap has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Your Gradle JDK is set to Java version 8 (52), you should be using Java 11+ (55) to build using loom in general, and Java 17+ (61) to build for Minecraft 1.18

@DoctorApparatus Were you able to get 1.18 main to build, and can we close this issue?

Closing issue due to no response