Face-based unlock systems probably shouldn’t work when the owner of the phone isn’t, you know, conscious. Some camera authentication tools work like that, but not Google’s Pixel 4 phones, which rather proudly replaced their fingerprint biometrics with front-facing cameras and sensors last year. The April security update fixed the oversight.
The Pixel 4 and Pixel 4 XL now have an option in the Security settings menu that will refuse to unlock via face authentication unless the operator has their eyes open. It’s a handy addition to the system if you store sensitive info on your phone and/or you don’t trust your significant other. A few other tweaks, like Bluetooth and keyboard bug fixes, are rolling out to older Pixel phones as well.