GA4 began using aggregate identifiers to attribute Google Ads traffic when GCLID is unavailable

Google Analytics now leverages aggregate identifiers (e.g. gbraid, gad_ parameters) as a fallback so paid Google Ads traffic is attributed to source, medium, campaign and channel even when the click ID cannot be used, such as when users deny ad_user_data consent. Advertisers should keep auto-tagging on and link Ads to Analytics.

Part of a broader April 2025 data-quality push Google described in its help center: aggregate identifiers and smart fallbacks (including manual UTMs) for data completeness, clearer '(data not available)' / '(not set)' labels, a data quality indicator menu, and system-generated annotations when attribution changes shift reported data. Traffic previously mis-labelled as organic can now show as paid Google Ads traffic, so expect step changes in channel reports.