Improvement
Teams Private Channel Migration
Previously, Teams private channel migration has to be done via the PowerShell Script MWTeamsPrivateChannelMembers.ps1 or Advanced Options which are now obsolete.
For Teams to Teams migration projects created after Aug 25, 2021, private channels are now migrated by default when the Teams and Channel Memberships item type is selected for migration.

Prerequisites
- Ensure UserMapping is set up properly prior to starting the migration
- Migrate Teams and Channel membership only as the last step with Planner. Refer to ‘Recommended Migration Steps’
Refer to the Teams to Teams migration guide for more information.
Private channel migration can be skipped by adding this new Advanced Option: TeamsSkipPrivateChannel=1
However, for existing Teams to Teams projects created before Aug 25, 2021, private channels will not migrated by default. The following Advanced Options must be added to migrate private channels:
TeamsMigratePrivateChannel=1
TeamsMigratePrivateChannelPermissions=1