The best decoder is prevention. Avoid proprietary encoded scripts unless you trust the vendor to provide source code escrow or long-term support.
Running a random "decoder script" on your PHP 7.2 server is a catastrophic idea. Most such tools are backdoors: they will decode your file (if lucky), but also send a copy to an attacker, or install a web shell. ioncube decoder php 72
Decoding may be legitimate when: