Ahrefs says Google poisons 5% to 20% of SEO tool results and is correcting stored rankings

Ahrefs told customers on October 22 that Google is showing different search results to suspected SERP data providers. It puts the affected share at between 5% and 20% of results, depending on the data provider. The company says it rejects abnormal pages, requests accurate replacements and is cleaning up past results that may have been affected. PPC Land reported the statement.

What is new

Other vendors described filtering new data. Ahrefs is the first in PPC Land's coverage to say it is going back over data it has already stored. Historical rankings in Ahrefs for the affected weeks may therefore change after the fact.

The statement leaves the important parts open:

• no methodology, sample size or start date

• no word on which provider sits at 5% and which at 20%

• no word on how far back the cleanup reaches, how many results were replaced, or whether corrected data points will be flagged

• no list of affected products, although Ahrefs' SERP data also feeds keyword difficulty, traffic estimates and AI Overview tracking

How it compares

Nozzle found swapped results on 8% of pages, with a single-day peak of 27.0% on September 29. DemandSphere reported wrong results on about 11% of its daily rank checks. AccuRanker measured rates under 1% in mid-October. The first two fall inside Ahrefs' band and the third falls below it. That fits AccuRanker's argument that the poisoned share depends on how data is collected.

Why it matters for AI visibility reporting

Google's September spam update ran from September 24 to October 8, the same weeks swapped pages entered vendor data. A drop in that window could be a real demotion, a blocked collection or a page Google served only to a suspected bot.

If you compare classic rankings with AI Overview citations or ChatGPT and Perplexity mentions, the ranking side of that comparison is the uncertain one for September and October. Google's own data does not close the gap. Search Console covers only verified sites, and its generative AI report shows impressions without clicks or queries.

What to do

• Date-stamp every ranking export and keep the file. A chart sent to a client in early October may no longer match the same chart in Ahrefs today.

• Treat any drop between September 24 and October 8 as unconfirmed until you have checked it against Search Console for that property.

• Watch Ahrefs' dashboard notifications. The company says further updates will appear there.

• Ask your rank tracking vendor what share of its data was affected, and on which dates.