HTML Guide for user-scalable
A <meta name="viewport"> element has been found where the allowed values for the viewport prevent users from zooming and scaling the document.
The user-scalable="no" parameter disables browser zoom on a web page. The maximum-scale parameter limits the amount the user can zoom. Both are problematic for users with low vision who rely on browser zoom to see the contents of a web page. Consider relaxing these values in order to allow users to resize the documents.