Understanding how to diagnose Facebook Ads reach drops in 2025 is essential for media buyers facing unexplained audience shrinkage and performance cliffs. Facebook's algorithm and policy enforcement have become increasingly strict, meaning campaigns that performed well months ago may now encounter sudden reach restrictions without clear warning signals. This guide walks you through the diagnostic process—identifying whether your account is flagged for policy violations, audience quality issues, or creative relevance problems. Media buyers will learn to distinguish between platform-side throttling and account-level restrictions, a critical skill that saves weeks of wasted budget. The framework provided helps you isolate root causes before implementing recovery tactics, ensuring fixes target the actual problem rather than symptoms.