As per your concern, we would request you to kindly perform the following steps to resolve your issue.
If you are having difficulty unlocking with Face recognition, try the face registration again. Remove the current face data by opening Settings, and then tapping Security and Privacy. Tap Biometrics, then tap Face Recognition, and then enter your credentials. You can now tap Remove face data to clear the facial recognition data so that you can have a fresh start.
Tips for Facial recognition:
Show your face and your device unlocks: it doesn't get much easier than that. If you are having some difficulty, here are some facial recognition tips. 1. Glasses, hats, masks, makeup, bangs, and beards can affect the recognition process. Adding an alternative look can help the device recognize you in different situations. 2. Make sure you are in a well-lit area and the camera lens is clean. 3. For best results, make sure your image is not blurry.
If the issue still persists kindly report the problems of your Samsung smartphone with a log file. To share a log file, click on the Samsung Members Application (Open Samsung Members Application > Support> Tap on error report > Type your query > Send).
