Snippet to show which template is currently being used.

functions.php

<?php 

    add_action('wp_footer', 'show_template');
    function show_template() {
        global $template;

        echo '<div style="width: 50%; margin: 40px auto; font-size: 12px; color: #c09853; background-color: #fcf8e3; border: 1px solid #fbeed5;padding: 2em; border-radius: 4px;"><p><strong>Current Template</strong></p><em>';
        print_r(str_replace(get_template_directory(), '', $template) );
        echo '</em></div>';
    }
    
?>