感谢@rilwis。get_current_screen() 返回一个页面对象，我可以从中检查其id，我认为它是唯一的！

function dont_update_plugins() {
    $screen = get_current_screen(); 
    if($screen->id == "plugins"):?>
        <div class="updated">
            <h3><?php _e( \'Please do not update plugins!\', \'my-text-domain\' ); ?></h3>
        </div>
    <?php endif; 
}
add_action( \'admin_notices\', \'dont_update_plugins\' );