PHP 7.4 brought massive architectural changes to the PHP ecosystem, including preloading, typed properties, and covariance/contravariance. IonCube updated its encoder (Version 10.4 and later) to fully support these PHP 7.4 features.
So, what are the search results for an "IonCube Decoder 7.4" actually showing you? They are almost exclusively pointing to third-party, unofficial, and often malicious tools that claim to crack or reverse-engineer the ionCube protection for a specific version, in this case, version 7.4. Ioncube Decoder 7.4
: Standard PHP code is compiled into opcode by the Zend Engine at runtime. IonCube compiles this code beforehand into a proprietary bytecode format. in this case