Microsoft Ignite shared that customer key support for the Microsoft Teams will become available for public preview at the end of 2020, now it is in for a public preview.
Microsoft Teams keep data safe by encrypting at rest in Microsoft data center starting with volume level encryption enable through BitLocker while servicing encryption. Customer key built on service encryption and provide an added layer of encryption in application level for data at rest and allows you as the organization to control their encryption keys.
Customer key help to meet compliance obligations because Microsoft 365 controls their encryption keys to encrypt and decrypt data and enhancing the ability to meet the demands of compliance requirements with the cloud service provider.
Teams will be offered as previews that are OneDrive, SharePoint Online, and Exchange Online. Assign a single data and correction policy at the tenant level to encrypt your data-at-rest in Teams and Exchange. See for a more detailed overview of the customer key for Microsoft 365 at the tenant level.