Fresh install, after adding a custom post type: Rank Math error

Dear support,

Today I started a fresh WordPress install, and immediately added a Custom Post Type and Rank Math.
However, after saving the custom code in functions.php. I get an error that originates from the Rank Math plug-in.

Notice: CMB2_Field::__construct() was called with a parameter that is deprecated since version 2.2.3! Using the "default" field parameter as a callback has been deprecated in favor of the "default_cb" parameter. in /data/sites/web/WEBSITE/subsites/dev.WEBSITE.nl/wp-content/plugins/seo-by-rank-math/vendor/cmb2/cmb2/includes/CMB2_Base.php on line 456

Warning: Cannot modify header information - headers already sent by (output started at /data/sites/web/WEBSITE/subsites/dev.WEBSITE.nl/wp-content/plugins/seo-by-rank-math/vendor/cmb2/cmb2/includes/CMB2_Base.php:456) in /data/sites/web/WEBSITE/subsites/dev.WEBSITE.nl/wp-admin/includes/misc.php on line 1196
S

This is the code for the custom post type registration:

/* Register custom post type 'blog' */
function blog() {

	$labels = array(
		'name'                  => _x( 'Blogberichten', 'Post Type General Name', 'cpt-namespace' ),
		'singular_name'         => _x( 'Blogbericht', 'Post Type Singular Name', 'cpt-namespace' ),
		'menu_name'             => __( 'Blogberichten', 'cpt-namespace' ),
		'name_admin_bar'        => __( 'Blogbericht', 'cpt-namespace' ),
		'archives'              => __( 'Blog archieven', 'cpt-namespace' ),
		'attributes'            => __( 'Blog attributen', 'cpt-namespace' ),
		'parent_item_colon'     => __( 'Parent blog', 'cpt-namespace' ),
		'all_items'             => __( 'Alle blogs', 'cpt-namespace' ),
		'add_new_item'          => __( 'Nieuw blogbericht toevoegen', 'cpt-namespace' ),
		'add_new'               => __( 'Nieuwe toevoegen', 'cpt-namespace' ),
		'new_item'              => __( 'Nieuw blogberichten', 'cpt-namespace' ),
		'edit_item'             => __( 'Bewerk blogbericht', 'cpt-namespace' ),
		'update_item'           => __( 'Update blogbericht', 'cpt-namespace' ),
		'view_item'             => __( 'Bekijk blogbericht', 'cpt-namespace' ),
		'view_items'            => __( 'Bekijk blogberichten', 'cpt-namespace' ),
		'search_items'          => __( 'Zoek blogbericht', 'cpt-namespace' ),
		'not_found'             => __( 'Not found', 'cpt-namespace' ),
		'not_found_in_trash'    => __( 'Not found in Trash', 'cpt-namespace' ),
		'featured_image'        => __( 'Featured Image', 'cpt-namespace' ),
		'set_featured_image'    => __( 'Set featured image', 'cpt-namespace' ),
		'remove_featured_image' => __( 'Remove featured image', 'cpt-namespace' ),
		'use_featured_image'    => __( 'Use as featured image', 'cpt-namespace' ),
		'insert_into_item'      => __( 'Insert into item', 'cpt-namespace' ),
		'uploaded_to_this_item' => __( 'Uploaded to this item', 'cpt-namespace' ),
		'items_list'            => __( 'Blogberichten list', 'cpt-namespace' ),
		'items_list_navigation' => __( 'Items list navigation', 'cpt-namespace' ),
		'filter_items_list'     => __( 'Filter items list', 'cpt-namespace' ),
	);
	$args = array(
		'label'                 => __( 'Blogbericht', 'cpt-namespace' ),
		'description'           => __( 'Blogberichten', 'cpt-namespace' ),
		'labels'                => $labels,
		'supports'              => array( 'title', 'editor', 'thumbnail', 'comments', 'custom-fields' ),
		'taxonomies'            => array( 'category', 'post_tag' ),
		'hierarchical'          => false,
		'public'                => true,
		'show_ui'               => true,
		'show_in_menu'          => true,
		'menu_position'         => 5,
		'show_in_admin_bar'     => true,
		'show_in_nav_menus'     => true,
		'can_export'            => true,
		'has_archive'           => true,
		'exclude_from_search'   => false,
		'publicly_queryable'    => true,
		'capability_type'       => 'post',
	);
	register_post_type( 'blog', $args );

}
add_action( 'init', 'blog', 0 );

I repeat that this is a fresh install (empty theme also), with ONLY Rank Math activated, and this custom post type.
When I remove the Custom Post Type registration code from the functions.php file, the error is gone.

I really love the plug-in, and would love to keep using it. How do I fix this error?

Kind regards