Update 6:51PM 12/15/20 The issue has been resolved.
As of 4:29PM 12/15/20 Google is working on a Gmail service disruption. While the system is working, some users are seeing error messages, slowness and other odd behavior. Google indicates they are still working on it and a resolution for all users is expected soon. For more about this outage, see Google's status page for this issue. As always, you can check all Google Workspace App Status Dashboard.