Semrush has acknowledged that some Google ranking data collected by automated tools can be distorted by “poisoned SERPs.”
The company’s October 27 update says some automated Google requests may return results pages that look normal but differ from what a typical user would see. Semrush described the issue as an industry-wide problem for SEO data providers and said it has added validation checks, filters clearly invalid results, and recollects potentially inaccurate pages.
Semrush did not say all of its ranking data is wrong. Its own data documentation says its keyword analytics and ranking reports rely on third-party providers that collect Google search engine results pages for hundreds of millions of popular keywords and record top-100 positions. If that collection receives a normal-looking but abnormal results page, a report can look precise and carry no warning while still being based on a bad observation.
Why the issue can lead to bad SEO decisions
A false ranking loss can trigger client concern, performance questions, emergency technical audits, content rewrites, or link investigations aimed at a problem that did not exist. For an agency, it can also make good work look weaker than it was. For an in-house team, it can send time and budget toward the wrong fix.
The same risk cuts the other way. A false gain can make weak work look successful, delay needed improvements, or make competitor movement look more dramatic than it is.
Other vendors are reporting similar patterns
AccuRanker reported that, on October 24, 40% of its first desktop fetches in its monitored sample were poisoned before checks. After its validation process, 3.2% of desktop keywords in that sample still had a swapped page one. The company said the next day’s stored desktop rate was below 1% again.
Nozzle’s October research used a different method and reported higher rates. It said it analyzed 29.9 million SERPs and found that, among SERPs judged on both page one and page two, 22.6% were poisoned since September 13, with a 43.5% peak on September 30. Nozzle also examined keywords where the tracked site normally appeared in the top 10. In that group, it was outside the top 10 on 60.8% of poisoned SERPs, compared with 2.7% in the baseline.
A same-day analysis from GrowByData on October 30 added another recent dataset, covering approximately 2.1 million Google SERPs collected from June 1 to October 27. It found abnormal-result rates rising in late September across monitored markets and staying above its roughly 1% summer baseline in its latest weekly readings, including Canada at 1.9%, the United States at 3.5%, the United Kingdom at 9.1%, and Ireland at 10.2%.
Those figures are not directly interchangeable because each vendor used its own collection process, sample, and detection method. Taken together, they show that Semrush is not describing a one-platform reporting bug. Rank-tracking data across the SEO software market is under more pressure than usual.
The suspected cause is not confirmed by Google
Semrush said industry discussion suggests a likely driver is an effort to limit large-scale data collection for AI systems, but it also said Google had not publicly commented as of its October 27 post. AccuRanker described anti-scraping pressure as one possible explanation, with rank trackers caught in the middle.
That leaves an evidence gap. Public reports from SEO data vendors show distorted results in their own collections, but the cited sources do not include a Google statement confirming the intent, duration, or full scope of the behavior.
The timing complicates spam-update reporting
The measurement problem overlaps with a real confirmed Google update. Google’s Search Status Dashboard says its September 2026 spam update began on September 24 and ended on October 8. Tech Help Canada’s Google Search updates tracker records that official update window for readers comparing ranking movement against confirmed Google rollouts.
That overlap creates a reporting trap. A site may have changed because of the spam update, normal volatility, a technical issue, seasonality, or a poisoned SERP captured by a tool. A third-party rank drop during late September or October should not be treated as proof of a Google penalty without corroborating data.
A safer way to read ranking reports
A rank tracker can still be useful for direction, competitive monitoring, and historical context. The immediate fix is to downgrade single-source, single-day movement from fact to lead.
Semrush told users to compare unexpected ranking changes against their own data, such as Google Search Console, especially when rankings shift for keywords unrelated to the affected pages.
Search Console comparison: Teams should compare clicks, impressions, and average position for the affected query and page.
Traffic check: Organic sessions, leads, sales, and conversions should be reviewed before a ranking chart drives a business conclusion.
SERP review: If the tool stores a captured SERP, reviewers should look for unrelated pages, wrong-location results, or usual competitors disappearing together.
Trend check: A one-day drop that reverses quickly deserves different treatment from a persistent decline across several dates.
Vendor questions: Agencies should ask rank-tracking vendors whether suspect SERPs are rechecked, filtered, or recollected before they appear in reports.
Google’s Search Console documentation describes Performance reports as showing how often site links appeared in Search, whether users clicked, and related query or position data. Those metrics are not a perfect replacement for rank tracking by exact location, device, and collection time, but they are a stronger corroborating source than a standalone third-party ranking chart.
For agencies, the safest language is conditional until the pattern is confirmed: the tool reported a drop, Search Console did or did not support it, traffic did or did not move, and the captured SERP did or did not match the query. That distinction can prevent unnecessary work and protect performance reviews from being driven by a faulty measurement.
Get new small business insights by email
Practical ideas and useful articles to help you make better business decisions.
Tech Help Canada Staff researches, writes, and reviews practical content for business owners and professionals. Our coverage spans business, marketing, SEO, technology, and the tools and systems people use to grow and operate online. We focus on clear, useful information backed by research, hands-on experience, and editorial review. Learn more about our team and editorial standards. Need help with something? Contact Us
