I did review your help articles, but I can't find the solution for this problem. My iPhone also does show this error which leads me to conclude that this malfunction could be a glitch with the latest macOS 11.2.1 software as another commenter on this thread has suggested. This does affect functionality I added an event to the Google calendar on my Mac, yet the event won't sync/show on my iPhone. This does not solve the problem once the Google calendar populates and appears to be working again, the error reappears after some time. I have removed and re-added the Google/Gmail account a few times now through System Preferences. I called Apple Tech Support, and they did not have a solution. This isn't happening to any of my other e-mail accounts.
I'm seeing the same error message for my Google Calendar while inside the Calendar app. I just purchased a new MacBook Air (M1 chip) and used Migration Assistant to transfer over from my old Air a little over a week ago.
