I’m not sure what the original issues were either but I do remember the message on the TrueCrypt site that said something like “warning, do not use. Contains unfixed security issues.” The only thing that might explain that is this line from Wikipedia: “TrueCrypt includes two vulnerabilities in the driver that TrueCrypt installs on Windows systems allowing an attacker arbitrary code execution and privilege escalation via DLL hijacking” Personally I believe the guy just didn’t want to maintain the thing anymore and abandoned it with no notice. Either way. Good thing VeraCrypt took over and fixed all those issues.
I’ve been using podman desktop (https://podman-desktop.io/) which is also free. I’ve never heard of rancher desktop so I’ll have to give that a look!