I lost my phone in a taxi and blocked it using Find My Device. I managed to get it back but now it has a button to call my home and a lock icon, but won't unlock.
You must restart your phone. Turn it off. When you turn it on again you'll be able to enter your password.
Maybe you don't need to restart your phone after login in "Finde My Device". The restart allows you to enter your device with your password, but sometime latter it will be blocked again. You must really go to the "Find My Device" web page.