Big Sur google mail issues-labels mailboxes deleted

Recently upgraded my 2009 Imac to a new 2019 with Big Sur. I have had separate labels/mailboxes on my google account for years, all gone.

I was having issues with an archive file duplicating everything. An Apple rep tried to help me with the google mail settings. All of the emails are gone. Google is zero help for recovery.

Any ideas please let me know. Seriously thinking about returning the Imac, Apple support has gone down hill in my opinion and mail issues with Big Sur seem to be an issue they haven't addressed.