Microsoft already disabled the basic authentication with Exchange Online. — If you came late to this party, this is related to this article Deprecation of Basic authentication in Exchange Online
Important If Basic authentication has been disabled in your tenant and users and apps are unable to connect, you have a…learn.microsoft.com Where is textually saying: “We’re removing the ability to use Basic authentication in Exchange Online for Exchange ActiveSync (EAS), POP, IMAP, Remote PowerShell, Exchange Web Services (EWS), Offline Address Book (OAB), Outlook for Windows, and Mac.