According to JEP 492 spec https://cr.openjdk.org/~gbierman/jep492/jep492-20241101/specs/flexible-constructor-bodies-jls.html,

If S is a local class whose declaration occurs in a static context, let N be the nearest static method declaration, static field declaration, or static initializer that encloses the declaration of S. If the nearest static method declaration, static field declaration, or static initializer that encloses the class instance creation expression is not N, then a compile-time error occurs.

So this code should fail, but it compiles:

class O {
    static void foo(int x) { // static context, so no enclosing instance
        class C { /* capture x */ }
        class U {
            static void test() {
                class L extends C {
                    L() {
                        super();// compilation succeeds
                    }
                }
            }
        }
    }
}

java --version
java 24-ea 2025-03-18
Java(TM) SE Runtime Environment (build 24-ea+26-3339)
Java HotSpot(TM) 64-Bit Server VM (build 24-ea+26-3339, mixed mode, sharing)