Async load and $Handle name

Hi, what’s is $handle name of plugin?
Despite the fact that q2w3 supports defer/async load, my console.log show error of not loaded jqury for q2w3. So, i want to make it wait for jquery library with forcing defer in functions:

function namespace_async_scripts( $tag, $handle ) {
    // nothing done, q2w3-widget-fixed might not be correct name
    if ( 'q2w3-widget-fixed' !== $handle ) { 
        return $tag;
    }
  if(is_front_page()){ return $tag;}
  else {return str_replace( ' src', ' defer src', $tag );}
}
add_filter( 'script_loader_tag', 'namespace_async_scripts', 10, 2 );

There are string wp_enqueue_script(self::ID, plugin_dir_url( __FILE__ ) . 'js/q2w3-fixed-widget.min.js', array('jquery'), self::VERSION, true); , but I don’t get out from it what handle name is?