Using Classic Outlook on Windows for personal email, calendar, and contact management
@Tom Womack said
Outlook repeatedly / randomly asks for my Yahoo Mail password multiple times each day
See some other recent cases where a Yahoo account will suddenly start losing authentication. Seems to be a Yahoo issue since users with multiple Yahoo accounts on the same Outlook client only have the problem with one account.
If you're using a Yahoo App Password, try generating a new one and updating Outlook to the new password.
If that doesn't help, come back here and we'll talk about creating a new profile and using OAuth instead of a password.