You can tick off this task if you do not want to use biometric features to unlock your device at all.
In Germany, for example, the police are allowed to use a suspect's finger to unlock their smartphone. As politically active people have a high risk of police contact, they should refrain from using biometric features for unlocking.
Refugees sometimes have their phones taken in order to clarify their origin or identity. Here too, authorities are allowed to use people's fingers to unlock the device.
People affected by digital violence or violence in relationships should refrain from using biometric features for unlocking. Unintentionally placing a finger on your phone while you sleep or unlocking it with images could lead to data being searched or unwanted software being installed.
Fingerprints and facial recognition are not secure methods for unlocking your device. They are like passwords that you can never change. It's not just data leaks or malware that could cause this sensitive information to be lost. Even pictures you publish yourself that show your fingers or your face could put you at a disadvantage.
In some countries, the police are also allowed to use your fingerprints to unlock your device. There have already been court rulings on this in Germany and the USA.
If you have an iPhone, you can temporarily lock Face ID and your fingerprint by pressing a special key combination. For Android, lockdown mode is available on some devices, allowing you to quickly disable biometric features in an emergency. You can find out more about this in the links below.
GrapheneOS offers you the option of using biometric features together with other unlocking methods. For example, you can set that your fingerprint is no longer accepted after a certain time and you have to enter a password instead.