Code-Snippets-Functions/Execute a function on a child site/WooCommerce/postmeta-form-limit-custom-fields-wp-admin-improve.txt

add_filter( 'postmeta_form_limit', 'limit_postmeta_keys_to_zero', 10, 1 );
function limit_postmeta_keys_to_zero( $limit ) {
    global $post;
    // Only for these post types
    $valid_post_types = array(
        // WooCommerce Subscriptions
        'shop_subscription',
        // WooCommerce
        'shop_order',
        'shop_coupon',
        // Sensei
        'course',
        'lesson',
        // WordPress
        'page',
        'post'
    );
 
    if( is_admin() ):
        if( in_array( $post->post_type, $valid_post_types ) ) {
            return 0;
        }
    endif;
 
    return $limit;
}