Why can other people unlock the POCO F6 Pro by fingerprint?

Please check whether you have turned on the Face unlock feature or the Unlock with Bluetooth device option. If either the face recognition or the Bluetooth device is recognized, a tick icon will appear at the top of the screen. In this case, if anyone else simply taps on the fingerprint recognition area, your phone will enter the home screen. To accurately diagnose any issues with the fingerprint unlock feature, it is essential to rule out other unlock methods first.
Please disable both the Face unlock and the Unlock with Bluetooth device features. After doing so, delete the existing fingerprints and add them again. This will help ensure that the fingerprint recognition process is not being affected by other unlock methods.