What about this notification Google sent recently ( see below for the gist)
Will Freenas start supporting OAuth to send emails?
Starting February 15, 2021, G Suite accounts will only allow access to apps using OAuth. Password-based access will no longer be supported.
We’re constantly working to improve the security of your organization’s Google accounts. As part of this effort, and in consideration of the current threat landscape, we’ll be turning off access to less secure apps (LSA) — non-Google apps that can access your Google account with only a username and password, without requiring any additional verification steps. Access through only a username and password makes your account more vulnerable to hijacking attempts. Moving forward, only apps that support a more modern and secure access method called OAuth will be able to access your G Suite account.
Access to LSAs will be turned off in two stages:
June 15, 2020 - Users who try to connect to an LSA for the first time will no longer be able to do so. This includes third-party apps that allow password-only access to Google calendars, contacts, and email via protocols such as CalDAV, CardDAV and IMAP. Users who have connected to LSAs prior to this date will be able to continue using them until usage of all LSAs is turned off.
February 15, 2021 - Access to LSAs will be turned off for all G Suite accounts.
What do I need to do?
To continue using a specific app with your G Suite accounts, users in your organization must switch to a more secure type of access called OAuth. This connection method allows apps to access accounts with a digital key instead of requiring a user to reveal their username and password. We recommend that you share the user instructions (included below) with individuals in your organization to help them make the necessary changes. Alternatively, if your organization is using custom tools, you can ask the developer of the tool to update it to use OAuth. Developer instructions are also included below.