Selectively Send Gravity Forms Notifications in Plain Text

functions.php

<?php

// Send Gravity Form notifications in plain text when Notification is called `Plain Text Notification`
add_filter( 'gform_notification', 'change_notification_format', 10, 3 );
function change_notification_format( $notification, $form, $entry ) {
    GFCommon::log_debug( 'gform_notification: change_notification_format() running.' );
    // Do the thing only for a notification with the name `Plain Text Notification`
    if ( $notification['name'] == 'Plain Text Notification' ) {
        GFCommon::log_debug( 'gform_notification: format changed to text.' );
        // Change notification format to text from the default html
        $notification['message_format'] = 'text';
    }
  
    return $notification;
}