As noted here:
https://mail.openjdk.org/pipermail/kulla-dev/2023-May/004236.html

--enable-preview and --execution=local do not work well together:

$ jshell --enable-preview --execution=local
| Welcome to JShell -- Version 21-internal
| For an introduction type: /help intro

jshell> var v = STR.""
v ==>

jshell> v.toString()
| Exception java.lang.UnsupportedClassVersionError: Preview features are not enabled for REPL/$JShell$189 (class file version 65.65535). Try running with '--enable-preview'
| at ClassLoader.defineClass1 (Native Method)
| at ClassLoader.defineClass (ClassLoader.java:1018)
| at SecureClassLoader.defineClass (SecureClassLoader.java:150)
| at DefaultLoaderDelegate$RemoteClassLoader.findClass (DefaultLoaderDelegate.java:156)
| at ClassLoader.loadClass (ClassLoader.java:593)
| at ClassLoader.loadClass (ClassLoader.java:526)
| at (#2:1)