Teams App Messages Captured by Microsoft 365 Substrate for Compliance Processing

The Microsoft 365 substrate now captures Teams app card data in compliance records to make the data available for eDiscovery, content searches, holds, and retention. The compliance records are stored in user and group mailboxes. Audit records for card interactions are also logged in the Office 365 audit log. Using compliance records means that some app data context is lost, but at least you can find the information.

https://office365itpros.com/2021/02/11/teams-app-data-compliance/