Looker Studio dashboards have not been moved as part of the Google Workspace migration.
Users should not lose access to the reports and dashboards as long as the linked dataset (spreadsheet) is owned by a Syensqo account.

Example A:

Looker studio Dashboard A is linked to a spreadsheet owned by a Syensqo user.
The Google Workspace migration tool has moved this spreadhseet over to the Syensqo Google Workspace domain on March 26th.
Access to Dashboard A is expected to remain.

Example B:

Looker studio Dashboard B is linked to a spreadsheet owned by a Solvay user.
The Google Workspace migration tool has NOT moved this spreadhseet over, it remains in Solvay's Google Workspace domain.
Access to Dashboard B is expected to be broken if a copy of the dashboard and the underlying spreadsheet was not made before March 26th.