Xiaomi
Add a Second Face Unlock Profile auf Xiaomi
Xiaomi phones running MIUI store only one face by default, which is why Face Unlock rejects you as soon as you change your appearance noticeably. Glasses, a beard, makeup, or a mask can be enough to break the match.
Registering a second face profile solves this without disabling security. The system simply compares incoming scans against both stored profiles instead of one.
Add the second face profile
Open Settings ➔ Passwords & security ➔ Face unlock. Confirm your identity by entering the current Pattern, PIN or Password when prompted.
Tap on Add face data. You will be asked again to enter the current Pattern, PIN or Password as a security check before a second face can be added.
Tap on Next and follow the on-screen instructions to scan your alternative look. Keep the phone at eye level and hold still until the scan finishes.
Once saved, MIUI checks new unlock attempts against both profiles automatically. If your device still fails to recognize either face reliably, poor lighting or a dirty front camera lens is usually the cause, not the stored data itself.