kint: Error message: Cannot access non-public member

I get this error. As I noticed, this only applies to static private property

An exception (ReflectionException) was thrown in phar://<ROOT>/wp-content/plugins/zu-plus/includes/debug/kint.phar/src/Parser/ClassStaticsPlugin.php on line 94 while executing Kint Parser Plugin "Kint\Parser\ClassStaticsPlugin". Error message: Cannot access non-public member zu_Plus::$zukit_root

What could be the problem?