Google has begun sending email notifications to advertisers about an upcoming update to Demand Gen Lookalike segments, following changes discovered earlier this week.
According to the email, starting March 15, 2026, Lookalike segments in Demand Gen campaigns will shift from strict similarity thresholds to audience suggestions. Instead of limiting reach to Narrow, Balanced, or Broad similarity tiers, seed lists will act as signals for Google AI, which can expand beyond selected thresholds to find additional qualified users.
Google says this change aims to improve performance by optimizing toward campaign goals such as conversions or CPA, unlocking inventory beyond traditional similarity limits.
Campaigns will migrate automatically on the effective date, though advertisers can opt out if they prefer to keep stricter controls.
Here’s the complete email shared by Arpan Banerjee and Adriaan Dekker.
