Unlike older PHP versions (5.x or 7.x) where numerous "Dezender" tools were publicly available, PHP 8.1 introduced a more complex bytecode structure.
To run files encoded for PHP 8.1, your server must have ionCube Loader v12 or higher installed.
However, the need for an often arises when developers lose access to their original source files, need to audit legacy code, or are migrating applications like WHMCS that transitioned to PHP 8.1. The Evolution of ionCube and PHP 8.1