I had a problem on my laptop where Outlook (I'm using Microsoft 365) wasn't syncing anymore .
it asked me to authenticate but it sent me to a Google prompt to enter my email and password. I successfully authenticated my account there, and of course Microsoft didn't accept it because my email account was set up using a Microsoft work account.
The problem happened because I had a SECOND Microsoft work account that I no longer used still provisioned on my laptop.
You cannot remove this account on the Settings>Email accounts page.
Instead, you must go to Settings>Accounts>Access Work or School and there you are allowed to remove the offending account.
Once I did that, Outlook didn't ask for authentication and everything was fixed.
I want to thank the Outlook team at Microsoft for helping debug this. They were stumped too, but got me to the right person.
This problem has existed for years apparently and nobody has posted the above fix.
I spent around 20 hours before I found the fix which was ridiculously easy once you knew where to look.
