Good evening.
If the login and password for the account are correct, you have also fulfilled all the requirements described in the link
https://support.google.com/mail/accounts/answer/78754Then make this mail inactive in the integration, uncheck "Active" for 3 days.
Then turn it on again.
Gool has this:
If there were a lot of invalid login attempts, then the host from which there were erroneous login attempts,
even with the correct data is not allowed.