How to Limit Teams Desktop Clients from Signing into Specific Tenants

A policy setting called RestrictTeamsSignInToAccountsFromTenantList is available to restrict the ability of Teams desktop clients to connect to Azure AD tenants. It’s a fact that floated under our radar for a while, but now that we know about it, we’re telling you too. Of course, you probably knew about this capability anyway, but someone probably didn’t!

https://office365itpros.com/2022/11/23/teams-client-sign-in-block/