We've 2 reports about this password issue in 78.4.0 in german support forums. When one account is set up to use OAuth2, the IMAP and POP accounts loose there login in every session, even though the passwords are stored in password manager. The reporters say that the problem will go away as soon as OAuth2's Yahoo account is switched back to password login (for testing purposes).
Bug 1673446 Comment 5 Edit History
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We've 2 reports about this password issue in 78.4.0 in german support forums. When one account is set up to use OAuth2, the other IMAP and POP accounts loose there login in every session, even though the passwords are stored in password manager. The reporters say that the problem will go away as soon as OAuth2's Yahoo account is switched back to password login (for testing purposes).