While organizations should always move to the strongest level of security controls, some key initiatives to expire legacy support is being extended to grant additional time for Microsoft customers due to the current pandemic

https://redmondmag.com/articles/2020/04/03/basic-authentication-exchange-online.aspx

Microsoft is now planning to disable Basic Authentication use with its Exchange Online service sometime in the “second half of 2021,” according to a Friday announcement.  The end date for Basic Authentication on Exchange Online previously was Oct. 13, 2020, but Microsoft is now pushing it out due to uncertainties surrounding the “COVID-19 crisis.”  The extension is just for organizations currently using Basic Authentication with Exchange Online.