I've seen other customers request this in this forum, but there is currently no Google Nest capability to use the "Familiar Faces" capability to turn OFF notifications when a familiar face is detected.
Thanks for your help, MplsCustomer.
We hear you. Our team is working hard to deliver the best experience for our users — we'll take this as feedback. Keep an eye on the Google Nest Community page https://goo.gle/2JvnMRy for any updates. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
Check out this link on how to file feedback.