You may have enabled 2-Step Verification.
then either configure it through the application password, or disable it and do like this
1. You need to disconnect mail from the CRM for a day, since the system has already tried to connect to Google many times and for a certain period of time you were banned
After 24 hours, need to do
2.
https://myaccount.google.com/securityAllow access to insecure devices
3. Follow the link
https://accounts.google.com/DisplayUnlockCaptchaClick
4. After that, just connect the integration again and everything will work) Provided that the accesses are really correct