What are Information Barriers in Microsoft Purview and how to make them work

According to Microsoft: “Microsoft Purview Information Barriers (IB) is a compliance solution that allows you to restrict two-way communication and collaboration between groups and users in Microsoft Teams, SharePoint, and OneDrive.”
Customize what happens at the end of the retention period using Power Automate

When you configure a ,retention label in MS Purview to retain items for a specific period, you specify what action to take at the end of that retention period. You can choose from the built-in actions, like permanently deleting the item, relabelling the item, deactivating the label, etc., but many administrators get somewhat challenged […]