the ongoing struggle for data ownership and transparency within the digital marketing ecosystem. It explains that "walled gardens", controlled by major platforms, limit brands' access to crucial performance data, making analysis and attribution difficult. Furthermore, the text highlights how some marketing agencies can inadvertently or deliberately create a secondary barrier by retaining control over client data. The document suggests that brands need to actively reclaim data sovereignty by owning accounts, securing contracts, building first-party data strategies, and leveraging solutions like data clean rooms to navigate these challenges and maintain strategic independence.