Many examples exist of PowerShell scripts which create reports about the membership of Microsoft 365 Groups. Most are slow. This version is faster because of its per-user rather than per-group approach to processing. The output is a nice HTML report and two CSV files containing a list of memberships in Microsoft 365 Groups and summary data for each user in the tenant.
https://office365itpros.com/2021/02/23/microsoft-365-groups-membership-report/
