foreach ($GLOBALS['TCA']['be_users']['types'] ?? [] as $type => $_) {
    $showitem = trim($GLOBALS['TCA']['be_users']['types'][$type]['showitem']);
    $showitem = sprintf('%s,%s', rtrim($showitem, ','), $auth0Showitem);
    $GLOBALS['TCA']['be_users']['types'][$type]['showitem'] = $showitem;
}