Special shout-out to
https://www.revouninstaller.com/I had a stubborn program remnant (after a system restore, windows 11). Setup woudln't continue until I uninstalled it. No files on disk. Nothing in system32 or hosts. Nothing in the registry (UFS Explorer Recovery Pro 8.2). Ever tried searching the registry on UFS? Sigh.
Registry cleaning with Wise Registry Cleaner? Nothing. iobit uninstaller? Nothing. Martau below? Nothing.
But RevoUninstaller's log based removal tool actually removed whatever the frack was bugging the setup. When on Windows 11, do keep an eye on folder protected actions and give access where requested (Defender).