I'm not a fan of the modal dialog (Authentication Code) on top of a modal dialog (File Services) on top of a modal dialog (Remote Files) on top of the application window.
It makes it feel that, rather than being intentionally designed, all of these features were tacked on.
I see the aesthetic concern. Although I am not really sure how that should be done. Regarding the totp specifically, if it is a situation that only happens with say 10% of the users of the google drive should it be included in the general dialog box and left blank if not used? Is there an established design for adding typically unused options? Error and highlight if you needed totp? I'm not sure if that is better.
This seems to be a fundamental design concern. I would love to see "good" examples of how to handle this.
It makes it feel that, rather than being intentionally designed, all of these features were tacked on.