Ticket #44849: test.php

<?php
/*
 * Plugin Name: Taxa context loss demo
 * Version: 1.0.0
 * Author: wallfur
 */

add_action('init', function() {
        register_post_type('foo', [
                'label' => 'Foo',
                'public' => true,
                'exclude_from_search' => true,
                'show_in_nav_menus' => false,
                'show_in_admin_bar' => false,
                'show_in_rest' => false,
                'menu_icon' => 'dashicons-palmtree',
                'supports' => [
                        'title',
                ],
                'rewrite' => [
                        'slug' => 'foo',
                        'pages' => false,
                ],
                'query_var' => 'foo',
                'delete_with_user' => false,
        ]);
        register_taxonomy('bar', 'foo', [
                'label' => 'Bar',
                'public' => true,
                'hierarchical' => true,
                'show_in_nav_menus' => false,
                'show_in_rest' => false,
                'show_tagcloud' => false,
                'show_in_quick_edit' => false,
                'show_admin_column' => true,
                'rewrite' => [
                        'slug' => 'bar',
                        'hierarchical' => true,
                ],
                'query_var' => 'bar',
        ]);
});