$ javap -v PrimitiveSwitch | grep -E 'minor|major'     (compiled by 25.0.4.1+1-LTS with --enable-preview)
  minor version: 65535
  major version: 69

$ java --enable-preview PrimitiveSwitch     (class compiled on 25, run on 27+35)
Error: LinkageError occurred while loading main class PrimitiveSwitch
	java.lang.UnsupportedClassVersionError: PrimitiveSwitch (class file version 69.65535) was compiled with preview features that are unsupported. This version of the Java Runtime only recognizes preview features for class file version 71.65535

$ java PrimitiveSwitch     (same class, no flag, run on 25.0.4.1+1-LTS)
Error: LinkageError occurred while loading main class PrimitiveSwitch
	java.lang.UnsupportedClassVersionError: Preview features are not enabled for PrimitiveSwitch (class file version 69.65535). Try running with '--enable-preview'