GSC DATA IS 75% INCOMPLETE

Summary from the TLDR Marketing newsletter

GSC is unreliable as a single source because Google filters about 75% of impressions and 38% of clicks for privacy. An analysis of 10 B2B SaaS sites with ~450M impressions found filtering from 59.3% to 93.6% for impressions and up to 88.5% for clicks, leaving large gaps in query data. AI Overviews surged in 2025 and correlate with a 56.6% click drop since March, while impressions fluctuated due to scraper activity. Bots also inflate impressions by 0.2% to 6.5%. Relying only on GSC can mislead teams, so use multiple data sources and sampling checks.