rwmb_meta_boxes filter

The code is something like this:

add_filter( 'rwmb_meta_boxes', 'test' );
function test( $meta_boxes ) {
	
	// Get current post ID
	$post_id = false;
	if ( isset( $_GET['post'] ) ) {
		$post_id = intval( $_GET['post'] );
	}
	elseif ( isset( $_POST['post_ID'] ) ) {
		$post_id = intval( $_POST['post_ID'] );
	}
	
    if ( get_post_status( $post_id ) != 'publish' ) {
    	$content = 'Not Published';
    } else {
    	$content = 'Published';
    }
    
    $meta_boxes[] = array(
        'title'      => esc_html__( 'Test', 'test' ),
		'post_types' => 'testtype',
		'context'    => 'side',
		'priority'   => 'low',
        'fields'     => array(
			array(
				'id'   => "_test",
				'type' => 'custom_html',
				'std'  => $content,
			),
		)
	);
	
	return $meta_boxes;
}

I know that is working fine. My issue is that I am getting an "Undefined variable: content" notice by Query monitor on WordPress posts.

My question is if there is any recommended way to make it run only on current custom post type? For example it also runs on post’s edit screen that's why I am getting the PHP notice. I am working on a multisite installation and the code is placed in a Plugin.

Thank you.

The current is the one that is defined in the rwmb_meta_boxes filter: 'post_types' => 'testtype'

I need to load the $content variable only on the testtype and not on the default post type.