Hi Lakshya,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
I'm sorry to hear you're having trouble with facial recognition on your Surface Pro 5. Here are some steps you can try to resolve the issue:
An important part of making Windows Hello secure, is that facial recognition must be confident that the face is a live person and not a photograph or other image. Facial recognition must have a clear view of your face. If facial recognition is struggling to recognize you, you’ll get the error message Couldn't recognize you. when you try to sign. If you can't sign in using facial recognition, sign in with a PIN or password instead, and then improve facial recognition.
Note: If your computer is managed by your work or school your IT administrator may have turned on enhanced anti-spoofing for Windows Hello. This sets an even higher standard for recognition and may especially cause problems in darkened rooms.
- To improve recognition, go to Settings > Accounts > Sign-in options > Facial recognition (Windows Hello) and select Improve recognition.
- If you're still having a problem with Windows Hello facial recognition, try running the troubleshooter that might fix the problem. Run Windows Hello troubleshooter
- Run the Surface Diagnostic Toolkit: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support
- Manually update Surface drivers and firmware: Download drivers and firmware for Surface - Microsoft Support
- As a last resort, If you've tried basic troubleshooting options, you may need to restore or reset your Surface. If the issue occurs after a reset, then the root cause is very likely hardware related. Restore or reset Surface for Windows - Microsoft Support
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist