Remove Visual Editor from Gravity Forms Notifications Page

functions.php

<?php
function remove_gf_notification_visual_editor($settings, $editor_id)
{
    if ($editor_id === 'gform_notification_message') {
        $settings['tinymce'] = false;
    }
    
    return $settings;
}

add_filter('wp_editor_settings', 'remove_gf_notification_visual_editor', 10, 2);