php-fpm missing include path for php 7.2

The include_path is not changed by Directadmin and it has a default value. It's not set in /usr/local/php*/lib/php.ini

The Directadmin PHP-FPM template does not have it in /usr/local/directadmin/data/templates/php-fpm.conf either.

So it seems you are right.

If you want to re-define it feel free to use either global php.ini or individual php-fpmXX.conf files.