-Authentication Basic

Basic authentication is being turned off, need to use Modern auth.

https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online

Here are the new commands, and the Basic one you're trying to use is also cited on this page so you can compare and decide how best to update your commands:

https://learn.microsoft.com/en-us/powershell/exchange/connect-to-exchange-online-powershell?view=exchange-ps

For us, we used Connect-MsolService -Credential $cred

All we had to do was change all those to Connect-ExchangeOnline - Credential $cred

And a few other commands then needed to be changed too, like Get-MailboxStatistics into Get-EXOMailboxStatistics. But not much really.

You can still use single factor accounts if you're worried about that, Modern Authentication doesn't mean forced to MFA.