The actual issue isn't that IonCube can't decrypt its own files on PHP 8.1; the issue is
: Add the following line as the very first entry in your php.ini file: zend_extension = /path/to/ioncube_loader_lin_8.1.so . ioncube decoder php 8.1
: It is a PHP extension that decodes and executes encrypted bytecode at runtime. Availability The Quest for an IonCube Decoder for PHP 8
Some popular IonCube decoders for PHP 8.1 include: ioncube decoder php 8.1
Summary
: These tools (often called "Dezenders") typically hook into the PHP engine to capture the bytecode before execution and attempt to reconstruct the original syntax.