Office 365 Groups (and their underlying teams and sites) can be removed by user action or automatically through the Groups expiration policy. By examining records in the Office 365 audit log, we can track exactly when groups are soft-deleted followed by permanent removal 30 days later. All done with a few lines of PowerShell and some parsing of the audit data held in the records.
https://office365itpros.com/2020/01/30/reporting-office-365-group-deletions/
