Enable OEM unlocking and follow the instructions. You might need to enter the PIN, password or pattern for unlocking the lock screen of your FP3

Try to https://www.fairphone.com/en/bootloader-unlocking-code-for-fairphone-3/ unlock Fairphone3

Input verify code : warning,
and ‘enable’ remains greyed out. No unlocking possible.

How to enable Input verify code ?

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone