WordPress, June 2025 – A bug in the Yoast SEO Premium plugin recently triggered concerns across the SEO community after it was discovered that AI-generated content produced through the plugin was quietly injecting hidden HTML classes into website content.
The issue surfaced after content audit expert Alan Bleiweiss flagged the bug on social media, noting that “AI wrappers”—technically HTML data attributes like data-start and data-end—were being automatically embedded in users’ posts without their knowledge or consent.
🛠️ What Happened?
When content from ChatGPT or similar tools is copy-pasted directly into a WordPress editor (without using the “copy” button), HTML formatting from the source can follow along. This includes classes or tags not visible on the frontend but present in the source code.
For instance, affected content would contain injected HTML like:
htmlCopyEdit<br data-start="57" data-end="60" />
While the published version appeared normal to users, SEO experts noticed these “fingerprints” as possible markers of AI-generated content.
What makes this bug critical is that it didn’t come from manual pasting—it was being automatically added by the Yoast SEO Premium plugin’s AI Optimize feature, a tool rolled out for the Classic Editor starting June 2nd, 2025.
🧩 Who Was Affected?
Only Yoast SEO Premium users were impacted, as the free version of the plugin doesn’t support AI text generation. However, Yoast rolled out an update (v25.3.1) swiftly after the issue came to light, assuring users that the fix would:
- Prevent further injection of unintended HTML classes
- Automatically remove existing injected data attributes from content
Yoast emphasized in their blog that while the classes were harmless from a visual standpoint, their presence was unintentional and inappropriate.
📉 Did It Affect SEO Rankings?
While the injected HTML classes likely didn’t impact the appearance or functionality of content, the bigger concern is whether they affected Google search rankings. Though unlikely, there’s no definitive confirmation that Google ignored the data attributes.
Given the increasing scrutiny of AI-generated content by search engines, even harmless anomalies could raise red flags in SEO audits.
🧪 A Pattern of Missed QA?
This isn’t Yoast’s first brush with buggy rollouts:
- March 2022 – An update created duplicate sitemaps.
- March 2018 – A bug resulted in thousands of thin image pages being generated.
This latest incident adds to the list of preventable issues that could have been avoided with more thorough pre-release testing—especially important now with AI involved in content creation.
✅ What You Should Do
- Premium Users: Update Yoast SEO Premium to version 25.3.1 immediately to avoid hidden HTML issues.
- Free Users: While unaffected by the AI bug, update for compatibility improvements.
- All Users: Avoid direct copy-pasting from AI tools into WordPress editors. Use the “copy” button or paste into plain-text editors first.
