The upgrade from PHP 7.4.20 to PHP 7.4.21 includes some bugfixes https://www.php.net/ChangeLog-7.php, which are breaking the smarty template includes. In our case ...

In the PHP world we have wonderful template engines/systems like Twig and Plates. If you need features like inheritance, extensions, built-in helpers etc. you should go with one of those. On the other ...