I'm not sure where to look to debug this, so looking for a clue.  Outgoing email was working, and the Test Connection still says it's working.  Sending messages seems to work in Odoo and the message is logged in the contact.  However, the message never gets received.

I'm guessing it's something I changed in Google GSuite settings, as I was working on routing to get incoming email to work.  That is now working, but outgoing isn't.