Oh interesting. Typically the gradle release notes, like 8.4-rc-1, will have comments that imply that Groovy build scripts compile but Kotlin ones lag.

"Gradle now supports using Java 21 for compiling, testing, and starting other Java programs. This can be accomplished using toolchains. Currently, you cannot run Gradle on Java 21 because Kotlin lacks support for JDK 21. However, support for running Gradle with Java 21 is expected in future versions."

https://docs.gradle.org/8.4-rc-1/release-notes.html#support-...