Basic authentication for Exchange Online was scheduled for removal on 13th of October 2020. This has now changed!
Due to the impact of Corona virus on customer focus, Microsoft has decided to postpone the decommissioning of basic authentication on Exchange Online until second half of 2021.
This means you have more time to migrate your Exchange Online scripts to the new Exchange Online Management PowerShell module (EXO V2). The EXO V2 module is still in preview and has full support for multi-factor authentication. It also has some cmdlets with improved performance.
Read the full statement from the Microsoft Exchange Team here.