Passing through PHX today and the TSA agent asked me to step in front of the camera for them to use their facial recognition. When I declined, the agent looked confused until I reminded him it's a voluntary program. That's when I noticed the signs communicating that to the public were not posted as they used to be. I noticed the same signs absent in Dallas a few weeks ago too. I stopped at the TSA desk and asked the agent in charge where the signs went. He said he thought they were somewhere out there but would check.

Keep in mind, you do not need to submit to this process. It doesn't delay you, cause extra security protocols, or anything else.