On prior versions you chose between either password or fingerprint authentication for the lockscreen. In Plasma 6, both are supported at the same time.
I've updated my Neon install, what do I need to do to enable this? I've set up a fingerprint through the user settings, but when the screen is locked I still have to use my password to unlock - there isn't a prompt, and touching the reader doesn't seem to do anything
Edit: follow up on an old post in case someone stumbles across it - I needed to install libpam-fprintd