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Starting in June 2020, we’ll limit the ability for less secure apps (LSAs) to access G Suite account data. LSAs are non-Google apps that can access your Google account with only a username and password. They make your account more vulnerable to hijacking attempts. Instead of LSAs, you can use apps that support OAuth—a modern and secure access method.
This is most likely to impact users of legacy email, calendar, and contacts apps—see below for more details. We’ve also emailed your organization’s primary admin with details around this change. That email includes a list of users who are likely to be affected."
"Update
March 30, 2020: We have suspended the turn-off detailed here until further notice. We'll announce new timelines on the G Suite Updates blog at a later date. For more details, see this post."
From here:
https://gsuiteupdates.googleblog.com...incorrect.html