Why is a new element created in the taxonomy when publishing a post in wordpress?

Question

WordPress

Created 2 types of post "Commercial premises" and "Slides".

function  register_post_type_appartment() {
    register_post_type( 'appartment',        
        array(
            'labels' => array(
                'name'  => 'Коммерческие помещения',
                'singular_name' => 'Объект',
                'menu_name'  => 'Коммерческие помещения',
                'name_admin_bar' => 'Объект',
                'add_new'  => 'Новый объект',
                'add_new_item' => 'Добавить новый объект',
                'new_item' => 'Новый объект',
                'edit_item' => 'Редактировать объект',
                'view_item' => 'Просмотреть объект',
                'all_items' => 'Все помещения',
                'search_items'  => 'Найти объект',
                'not_found' => 'Помещения не найдены.',
                'not_found_in_trash' => 'No found in Trash.'
            ),
            'public' => false,
            'show_ui' => true,
            'has_archive'	=> false,
            'hierarchical' => true,
            'menu_icon' => 'dashicons-admin-home',
            'capability_type' => 'post',			
            'menu_position' => 5,
            'supports' => array( 'title', 'revisions',  ) 
        )
    ); 
}

add_action( 'init', 'register_post_type_appartment' );

function  register_post_type_slides() {
    register_post_type( 'slides',        
        array(
            'labels' => array(
            'name'  => 'Слайды',
            'singular_name' => 'Слайд',
            'menu_name'  => 'Слайды',
            'name_admin_bar' => 'Слайд',
            'add_new'  => 'Новый слайд',
            'add_new_item' => 'Добавить новый слайд',
            'new_item' => 'Новый слайд',
            'edit_item' => 'Редактировать слайд',
            'view_item' => 'Просмотреть слайд',
            'all_items' => 'Все слайды',
            'search_items'  => 'Найти слайд',
            'not_found' => 'Слайды не найдены.',
            'not_found_in_trash' => 'No found in Trash.'
            ),
            'public' => false,
            'show_ui' => true,
            'has_archive'	=> false,
            'hierarchical' => true,
            'menu_icon' => 'dashicons-images-alt',
            'capability_type' => 'post',			
            'menu_position' => 6,
            'supports' => array( 'title', 'revisions', 'editor', 'thumbnail',  ) 
        )
    ); 
}
add_action( 'init', 'register_post_type_slides' );

These two types of posts have a common taxonomy "LCD" I create it like this

function register_taxonomy_complex() {
    register_taxonomy('complex', array('appartment', 'slides'), array(
        'label' => '',
        'labels' => array(
        'name' => 'Жилые комплексы',
        'singular_name' => 'Жилой комплекс',
        'search_items' => 'Найти ЖК',
        'all_items' => 'Все ЖК',
        'view_item ' => 'Посмотреть ЖК',
        'parent_item' => null,
        'parent_item_colon' => null,
        'edit_item' => 'Редактировать ЖК',
        'update_item' => 'Обновить ЖК',
        'add_new_item' => 'Добавить ЖК',
        'new_item_name' => 'Новый ЖК',

        'menu_name' => 'Жилые комплексы',
        ),
        'description'           => '',
        'public'                => true,
        'show_in_menu'          => true,
        'show_tagcloud'         => true,
        'show_in_rest'          => null,
        'rest_base'             => null,
        'hierarchical'          => false,
        'update_count_callback' => '',
        'rewrite'               => true,
        'capabilities'          => array(),
        'meta_box_cb'           => 'post_categories_meta_box',
        'show_admin_column'     => false,
        '_builtin'              => false,
        'show_in_quick_edit'    => null,
    ));
}

add_action( 'init', 'register_taxonomy_complex' );

I created a taxonomy in the admin panel, then I create either a slide or a room, put a tick on the desired LCD and when publishing, a new element is created in the taxonomy with a name number and a label number and the post is automatically assigned to it. If you go to the list of all objects in a specific post type and set the taxonomy for the post through the properties and update, then everything is fine. What could be the problem?