Prior to the change, tools could send a single request (with a parameter &num=100) to retrieve the top 100 organic results in one go.

After the change, this parameter no longer works (or works inconsistently). To get the same 100 results, tools now have to paginate (e.g. using &start=) essentially 10 separate requests instead of one.

Desktop impressions in GSC have dropped sharply for many sites starting from around Sept 10. Average position metrics have improved (i.e. numerically lower position values) in many cases.

Vendors that relied on the &num=100 parameter are seeing disruptions. Instead of one request fetching 100 results, they now need ten separate requests. That means slower updates, heavier infrastructure costs, and in some cases, less complete data.

Some tools are already considering limiting reporting depth (e.g. top 20 or top 50 results)

While the average position appears to improve. Clicks, however, have remained stable. What’s happening isn’t a real performance shift; it’s Google removing “phantom” impressions created by bots and bulk requests.

The upside is cleaner, more realistic data; the downside is confusion. Historic comparisons become less reliable.

For agencies and account managers, this change brings extra work. Clients who see impression drops may assume their SEO is failing, while “better” average rankings may look like progress that isn’t real. Without clear communication, trust can erode.

Smaller businesses may also struggle if tool providers raise prices. On the flip side, this is an opportunity for agencies to educate clients, reset baselines, and focus attention on metrics that truly matter - clicks, conversions, and visibility in the top 10–20 results where traffic actually happens.

Bot /scraping noise: Many believe Google removed the parameter to stop automated tools from inflating impressions (bots loading deep pages) and to reduce scraping.

Infrastructure/performance concerns: Supporting large result sets for many simultaneous users/tools strains resources. By limiting the result page size, Google can reduce the load. Not officially confirmed, but plausible.

Aligning metric reality: To make what is reported (impressions, average position) more reflective of what “real users” see (they rarely scroll far; they usually view the first page) rather than tool-driven data.

Preparing for changes in SERP layout / AI-driven interfaces: As Google increasingly uses AI Overviews and dynamic SERP elements, simplifying how SERP data is fetched and reported could help with newer formats.

Whether the change is permanent or still partially experimental. Some reports say inconsistent behaviour in certain regions / for certain queries.

The exact thresholds/policies Google is enforcing (e.g. rate limiting, device/login state/region differences).

Full data on how mobile impressions/positions are being affected (most of the early reporting focuses on desktop).

Set new baseline periods post Sept 10-14, 2025, so that reporting is comparing “apples to apples.” Annotate reports to show when the change came in.

Don’t panic at sudden drops in impressions, cross-check clicks, CTR, and conversions to judge performance.

Ask whether they’ve updated workflows to account for the removal of &num=100. See if they’ve shifted to pagination, sampling, or limited result tracking.

If you rely on deep keyword tracking (beyond top 20 or 50), understand what compromises you’ll have to accept (cost, latency, less frequent updates).

Prioritize high-impact keywords: top 10–20 positions usually contribute the lion’s share of traffic. Track those more closely.

For long-tail and competitive benchmarking, decide which ones still matter enough to track deeply, maybe restrict to weekly rather than daily, or sample rather than exhaust.

Add notes in client reports: “From mid-Sept 2025, Google deprecated &num=100 → this affects impression/avg position metrics.”

Visualize the change: graphs showing impressions/average position before & after change help illustrate the measurement shift.

Is tracking many keywords beyond the top 50 really worth the cost/complexity? It might be better to invest resources in optimizing your content/experience for higher positions + conversion.

Also consider diversification of data sources (other search engines, user behaviour metrics, first-party analytics) to supplement what SERP tools can show.

Keep an eye on Google’s Webmaster/Developer blogs.

Also monitor tool providers/industry forums: often when Google gradually rolls out changes, tools surface edge cases or workarounds

CheckList

GSC Rebaseline Notion Worksheet

Strategic Keyword Tracking Planner | Notion Template

Instant Manual Check Pre Sept 10 and Post Sep 15 | Vibe Coded Claude Visual Dashboard