This is one of the reasons why I've kicked everything Google to the curb. After years and years of receiving my server notices and log reports, Google changed something and they started getting rejected over a year ago. Even after using their supposed "automatic" form to clear things up (
https://support.google.com/mail/contact/bulk_send_new?rd=1), my emails from the server continued to be rejected. I switched to Outlook and haven't had an issue since then.
I watch my mail logs like a hawk. There are still times when Google gets stupid and notices from the forum start getting rejected. I then spend a good 2-3 days fighting with them to fix things on their end so the emails go through.