As you know, the “Basic Authentication” configuration was turned off last month.
Organizations using Exchange Online are now protected from the vulnerabilities of legacy authentication.
However, this closure process will continue On December 31, 2022, with exemptions.
Microsoft says ;
Once Basic auth for Outlook, Exchange ActiveSync and Exchange Web Services has been permanently disabled in your tenant, there’s really no reason to keep Autodiscover enabled for Basic auth. So, we’re turning off Autodiscover next.
For more details ;
Basic Authentication Deprecation in Exchange Online – What’s Next
Have a nice day !