On Plesk Obsidian with Cloudlinux we have a strange issue.
When running th edefault Plesk PHP version all extensions work when running as FPM and FastCGI.
However, when we set the PHP Selector to alt-php73 or alt-php74 there is strange behavior.
When runnning alt-php73 or alt-php74 as FPM by Apache everything works but when we run alt-php73 or alt-php74 as FastCGI then WordPress sites give errors stating the mysqli extension is not enabled.
The output of /opt/alt/php73/usr/bin/php -m and /opt/alt/php74/usr/bin/php -m clearly shows mysqli and mysqlnd
We have the same problem when running LSPHP73 or LSPHP74.