You have two options. 1. Allow it so Thunderbird can actually work. 2. Disallow it and remove the account from Thunderbird because it will not be functional so having it set up serves no purpose at all. You will be prompted for access every time Thunderbird attempts to get mail (default to every 15 minutes) or if you choose the option when setting up your account synchronize your contacts (every 30 minutes) or calendar, (also every 30 minutes). As I said above you have two option of stopping requests. There are occasions when things like VPN's and antivirus software causes previously allowed access to be revoked by Google. This is particularly so with the use of a VPN to hide your location from google. Your VPN says you are in Budapest and your phone also connected to google says you are in Atlanta. That rings alarms at google about you being hacked. Instant revocation of oauth tokens and a re-authentication is used to ensure you are actually you. So I do not knowe how you need to stop it, my gut tells me you have a VPN issue but I don't know.