Google Demand Gen Just Changed How Your Lookalike Audiences Work: What Every Ecommerce Brand Must Check Before Q4

On October 13, 2026, Google confirmed that lookalike segment targeting in Demand Gen campaigns now defaults to suggestion mode across all advertisers. For ecommerce brands running Demand Gen with first-party customer lists, this means the audiences you defined as strict boundaries -- Narrow (2.5% of users in your target location), Balanced (5%), or Broad (10%) -- are now treated as starting points, and Google's AI will expand delivery beyond those thresholds to find conversions.

What Does Google's Demand Gen Lookalike Change Mean for Your Campaigns?

Your Demand Gen campaigns may now be showing ads to users outside your defined lookalike audience boundaries. Google uses your seed list as a signal and finds additional users it predicts will convert, even if they fall outside the 2.5 to 10% similarity threshold you selected. If lookalike precision was core to your Demand Gen strategy, your campaign's audience composition may have already shifted without your knowledge.

What Exactly Changed and How Does the New Suggestion Mode Work?

Until this update, lookalike segments in Demand Gen acted as strict targeting constraints. If you set Narrow reach (2.5%), only users within that similarity band saw your ads. With suggestion mode now the default, Google's AI treats that lookalike as a directional signal. It still prioritizes users similar to your seed list, but it can expand beyond your selected reach level when it predicts a conversion opportunity exists.

You can identify whether your campaign is in suggestion mode directly in the Audience Reporting table. Any lookalike segment currently operating in suggestion mode will show a "signal" label next to it in that report. If you have not actively opted out, suggestion mode is active across all your Demand Gen lookalike segments right now.

This change sits on top of the existing Optimized Targeting setting in Demand Gen, which also expands beyond selected audiences. The combination means your Demand Gen campaigns now have two layers of AI-driven audience expansion running simultaneously unless you explicitly disable both. That is a meaningful shift in how much direct control you have over delivery -- and it matters a great deal for 7 to 9-figure brands running Demand Gen as a precision prospecting channel.

Google's rationale is improved conversion finding. The expanded flexibility allows the system to identify users with high purchase intent who share behavioral characteristics with your seed list but fall outside the strict statistical similarity thresholds. For brands with smaller or less diverse seed lists, this may improve reach quality. For brands targeting very specific high-value segments, it introduces audience dilution risk that needs active monitoring.

The rollout began in March 2026, meaning some accounts have been in suggestion mode for seven months. A critical detail: UI controls for opting out only became available in October 2026. Previously, the only way to restore strict targeting was to submit a form request to Google's support team, which most advertisers did not do. If your agency or internal team did not actively opt out, your Demand Gen lookalike campaigns have been in suggestion mode since March.

For a full chronological view of every Google Ads change this year, see our complete Google Ads 2026 update tracker.

How Can You Tell If Your Demand Gen Results Have Already Changed?

Pull your Demand Gen campaign performance segmented by audience in the Audience Reporting table. Look for the "signal" tag next to your lookalike segments. That tag confirms suggestion mode is active and has been influencing delivery. Compare conversion rates and CPAs from before March 2026 to the current period. If CPA rose without a corresponding improvement in downstream metrics like average order value or repeat purchase rate, audience expansion is worth investigating as a contributing factor.

Also review your audience size and impression share data. If your Demand Gen ads are reaching significantly more users than your defined lookalike population would allow, that confirms expanded delivery is happening. Volume going up while CPA holds is a green flag. Volume going up while downstream quality degrades is a red flag.

For brands running Demand Gen as a precision prospecting tool targeting specific high-value customer profiles -- say, customers of competing brands, or users who match your highest-CLV buyer segment -- cross-reference your CRM acquisition data from the March to October period against your expected ideal customer profile. If the cohort looks off, suggestion mode is the likely explanation.

What Should You Do Now with Google's Demand Gen Lookalike Change?

1. Check your Audience Reporting table today. Open any active Demand Gen campaign, navigate to the Audiences section, and look for the "signal" label next to your lookalike segments. This is your confirmation that suggestion mode is active and has been influencing delivery since March 2026.
2. Make a deliberate choice: stay in suggestion mode or opt out. If your Demand Gen campaigns are hitting ROAS targets and CPA is stable or improving, stay in suggestion mode and let Google's AI expand. If you are targeting high-specificity segments where audience dilution is a real concern, use the new UI controls in campaign settings to restore hard constraints on your lookalike segments.
3. Disable Optimized Targeting if you want strict control. Both suggestion mode and Optimized Targeting expand your audience beyond your selected parameters. Opting out of suggestion mode alone does not fully lock your targeting. Disable both in campaign settings if strict audience control is the goal.
4. Run a before-and-after CPA audit going back to March 1, 2026. Pull Demand Gen performance from Q1 2026 (before the rollout) versus the current period. If CPA has shifted by more than 15% and you have not made any other major campaign changes, audience expansion is worth investigating as a variable.
5. Make your decision before scaling Demand Gen for BFCM. If you plan to scale Demand Gen spend 2x or more for the holiday season, you want to know exactly what audience you are buying before you scale it. Scaling a suggestion-mode campaign into BFCM without understanding your actual delivery audience is a meaningful risk for brands investing six figures or more in Q4 Demand Gen.

Related Reading

• Google's September 2026 Demand Gen Drop: One-Click YouTube Shorts and Gmail Image Ads Every Ecommerce Brand Must Use Before Q4
• Google Is Adding AI Text to Your Demand Gen Videos by Default: What Ecommerce Brands Must Check Right Now
• CTC Google Ads Agency: How We Build Demand Gen Campaigns That Scale

Frequently Asked Questions

Want help auditing your Demand Gen campaigns before Q4? Talk to us -- our team manages hundreds of millions in ad spend across Google for 7 to 9-figure ecommerce brands and can walk you through exactly what this change means for your campaigns.