A good solution would be to add global directives to .htaccess that would allow you to change PHP versions without having to have them all installed for a particular user.

Currently, when you use automatic sub domain creation, to change the PHP version you have to refer in .htaccess to the installed PHP version for the user, not globally.

Example:

.
  SetHandler fcgid-script
  FCGIWrapper /var/www/USER/data/php-bin-isp-phpVERSION/php
.

If the user does not have PHP 7.4 installed, for example, then it can not set, first you need to install such a user PHP from the panel, and only then you can possibly change.