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It almost certainly changed what the campaign is allowed to serve on, not how it bids. A collapsing cost per click alongside exploding impressions is the signature of delivery shifting into cheap non-Search inventory.
On this page
- Why does Performance Max hide where the spend goes?
- How do I diagnose it?
- What did I get wrong the first time?
- What does connecting the Shopify Google channel actually change?
Why does Performance Max hide where the spend goes?
A Performance Max campaign reports one blended cost per click and one conversion count. Its YouTube, Gmail and Display spend is invisible at campaign level. So if delivery tilts toward cheap inventory, the campaign-level cost per click falls and impressions rise, and nothing in the default view tells you why.
How do I diagnose it?
Segment by ad network type. That is the whole answer.
| Network | What it means |
|---|---|
| Search | The slice that usually converts |
| Search partners | Third-party search |
| Content | Display |
| YouTube | Video inventory |
| Google TV | Connected TV |
| Gmail | Inbox placements |
| Discover | Discover feed |
Measured on a software affiliate account across 12 days, all 8 Performance Max campaigns: YouTube $680.53 for 0.3 conversions, Gmail $269.13 for 1.0 conversion, Display $0.02. That is $949.68 for 1.3 conversions, roughly $2,406 a month — while every other conversion in those campaigns came from the Search slice.
What did I get wrong the first time?
On the first pass of that read I mislabelled the network enums — I called one value Google TV when it was YouTube, and left another unresolved. Caught before any conclusion shipped, but it would have named the wrong channel in the fix. Resolve enum values against the library rather than assuming the ordering. An off-by-one in an enum is invisible and produces a confident, wrong answer.
What does connecting the Shopify Google channel actually change?
Connecting the channel app typically supplies a product feed and enables retail asset behaviour. A Performance Max campaign that gains a feed changes its eligible inventory. Check three things:
- Did the campaign gain a feed it did not have before?
- Did asset groups gain images or video that opened up non-Search placements? Google will auto-generate a video if you supply none.
- Did conversion tracking change? The app installs its own tracking. If a manual tag was already present, you now have two, and every order counts twice.
That third one matters most and is checked least. One test order should produce exactly one purchase conversion.
Related questions
How do I stop Performance Max from spending my budget on YouTube?
You cannot switch YouTube off inside a Performance Max campaign. What you can do is see exactly how much it is costing you, fix the signal that is sending it there, and decide whether to split the campaign. Read the full answer.
I increased my LSA budget 50% and barely got more leads — why did my cost per lead go up?
Because budget was not your constraint. If you were not paced out, extra budget buys you nothing except a higher position in auctions you were already winning — which costs more per lead without producing many more of them. Read the full answer.
Does a feed-only Performance Max campaign really only run on Shopping?
No. A feed-only campaign is weighted toward Shopping inventory, but it still serves across the Performance Max network — Google generates assets from your product data to fill the other placements. Read the full answer.
Written by Usama Khan, who runs Google Ads for e-commerce brands and home-services companies at AdventurAds. Figures are from accounts under active management and are anonymised. Last reviewed 2026-08-26.
