A warning has been posted by Google in the Google Search Console
data anomalies page that, starting on April 3, 2019, you can expect those reports to see an increase in the number of issues and affected items and/or pages. The reason behind this is that Google has began collecting data from more pages than previously.
The announcement. “April 3, 2019: For most enhancement reports, data is now being collected from more pages than previously reported. Because of this, you might see an increase in issues and affected items/pages on these reports,” Google wrote.
Google is making the attempt to give SEOs, webmasters, developers and site owners a heads up that if they see an increase in the numbers of issues and affected items or pages reported in these reports, it is something to expect. It’s possible that you’ll see a spike in errors beginning April 3rd because of the number of pages Google is looking at.
According to Google, this most affects the enhancement reports, which could includes reports such as the AMP report, mobile usability, products, jobs and others. Not much was said about which enhancement reports won’t be impacted.
So, if you see new errors pop up, chances are, they were already there and Google just didn’t report them. But because of this, you can now address these issues.