Persistent class uses static cache incorrectly, breaks under PHP8.1

final public static function properties_definition() {

    static $def = null;

  . When a method using static variables is inherited (but not overridden), the

    inherited method will now share static variables with the parent method.

        class A {

            public static function counter() {

                static $counter = 0;

                $counter++;

                return $counter;

            }

        }

        class B extends A {}

        var_dump(A::counter()); // int(1)

        var_dump(A::counter()); // int(2)

        var_dump(B::counter()); // int(3), previously int(1)

        var_dump(B::counter()); // int(4), previously int(2)

    This means that static variables in methods now behave the same way as

    static properties.