Diagnosing a performance drop

Conversions fell. As in SEO, the discipline is to rule out the boring causes before the interesting ones — and in paid media the most common cause is that nothing changed except the measurement.

1. Did tracking break?

Always first. A tag removed in a deploy, a consent banner change, a checkout change, a container edit, an expired offline import. The signature is clicks and spend flat, conversions down. If the ads are still being clicked at the same rate, demand did not vanish — the recording of it did.

Check the conversion action's status and recent conversion volume by action, not just the campaign total.

2. Is it a platform incident?

Platforms break, sometimes quietly. In August 2026 an AdMob bug halted rewarded video on Android for eight days — logged at 21:19 UTC on 20 August, then 160 hours without a status update, root cause eventually found, no workaround. Publishers who did not check the status dashboard spent that week investigating their own releases.

Check the status dashboard and the practitioner communities before assuming it is you.

3. Did costs change, or did conversion rate change?

Split the drop:

• CPC up, conversion rate flat — auction pressure. A competitor entered, or a bidding change altered what you pay. This is what the August 17 Smart Bidding change looked like in many accounts.
• CPC flat, conversion rate down — something after the click. Landing page, offer, stock, price, checkout.
• Impressions down — eligibility or demand. Check disapprovals, budget, and query volume.

These three have nothing in common, and the aggregate hides which one you have.

4. Did the account change?

Change history is the fastest read in Google Ads and almost nobody opens it first. Someone edited something — including automated rules, scripts, and increasingly AI agents with write access.

5. Did policy change?

Disapprovals and policy updates remove eligibility silently. Check the policy manager.

6. Only then: demand and seasonality

Compare against last year, not last month.

What trips people up

• Changing bids during the diagnosis. Now you cannot attribute the recovery.
• Reading account totals instead of segmenting by campaign, device, and network.
• Assuming your account is unique. If four practitioners report the same thing the same week, it is the platform.

You have got this when

Your first three checks are tracking, status dashboard and change history — before you touch a single bid.