The FullFix patch is not a standalone program but a collection of scripts and modified executables that interact directly with the Xentry installation. According to the official release notes on MHH Auto, applying this patch performs the following actions on a Windows 10 or 11 system running Xentry 2021-12:
Demystifying Full FreeFixXentry202112: The Essential Guide to Mercedes-Benz Diagnostic Activation full freefixxentry202112
He didn't delete it. Instead, he renamed the process. He gave it a new header that the automated cleaners would never touch, ensuring the "fix" would run forever. The FullFix patch is not a standalone program