Following the steps https://docs.microsoft.com/en-us/office/office-365-management-api/get-started-with-office-365-management-apis to complete Oauth flow and running into this error:
AADSTS54005: OAuth2 Authorization code was already redeemed, please retry with a new valid code or use an existing refresh token.
We are not reusing the code, the secret and cert on the app are valid and have not expired.
This worked previously with this app and only started erroring today.