@EpsilonAdmin hi there again. Fabulous!

Although I'm not exactly sure what enabling the extension actually does, luckily enough, I know enough to find and enable the extension within my cPanel interface.

I note that using PHP 8.1, the mbstring extension is enabled, but for some reason only known to GoDaddy, when version 8.4 is used, it de-selects mbstring (along with mysqli) making the website non-functional.

However, with your advice, the site is now back up and running. Thank you for the speedy and spot-on advice, very much appreciated.