Relying on the <base>
tag has been deprecated in Contao 5.0 and will no longer work in Contao 6. Use absolute paths
for links and assets instead.
Using the global $GLOBALS['TL_LANGUAGE']
has been deprecated in Contao 4.0 and
will no longer work in Contao 6.0. Use the locale from the request object instead:
$locale = System::getContainer()->get('request_stack')->getCurrentRequest()->getLocale();