WordPress Must Use Plugin which activate Contact Form 7 only on contact page.

tk-mu-plugins.php

<?php
/*
Plugin Name: TK-MU-Plugin
Description: 
Author: Thomas Krakow
Version: 1.0
Author URI: https://thomas-krakow.de/it/css-und-javascript-nur-bei-bedarf-auf-wordpress-seiten-einfugen/
*/

$fRequestURI = parse_url( $_SERVER['REQUEST_URI'], PHP_URL_PATH );
if( false === strpos( $fRequestURI, '/wp-admin/' ) ){		    
    add_filter( 'option_active_plugins', 'tk_activate_plugins' );
}

function tk_activate_plugins( $plugins ){
	    
    global $fRequestURI;
    $is_contact_page = strpos( $fRequestURI, '/kontakt/' );
    $is_rest_api = strpos( $fRequestURI, '/contact-forms/' );
    
    $k = array_search( "contact-form-7/wp-contact-form-7.php", $plugins );
    
    if( false !== $k && false === $is_contact_page && false === $is_rest_api ){
        unset( $plugins[$k] );
    }
    
    return $plugins;
}