fdesetup usage deprecated (seeking more information)

This page indicates https://support.apple.com/en-in/guide/deployment/dep0a2cb7686/web that some usage of fdesetup command line tool is deprecated such as turning on FV using username/password. However, I don't see any proper information about which options from the fdesetup tool are deprecated and which are still valid? Any pointers for that?

Thanks, N