www.makemkv.com

Whatever the cause or issue, the download availability is erratic and I suggest establishing an official mirror.

Anywhere I can get any reasonably recent Mac version? I don't even have an old copy I can use and there are no other download links I can find that are Mac-compatible and likely to be clean.

The link https://makemkv.com/download/makemkv_v1.17.3_osx.dmg (which is the MacOS installer link from the website) gives a generic 404 File Not Found error.