 This feature can be turned off. Make sure it's not. Head into Settings, then Face ID and Passcode. Look for Require Attention for Face ID. If it's turned off, toggle it on. Android phones have a similar feature. On Samsung, you can enable Attention Aware in the biometrics and security settings. Turn on Require Open Eyes to keep your phone locked tight. And here's a fun fact. Most facial ID systems can recognize you even if you grow a beard or wear glasses.