We recognize the frustration around limitations we’ve placed on this sized unit on mobile webpages, and starting May 2, 2017 we will no longer disallow this ad unit from being placed above the fold on mobile web pages. After careful review, we've determined that when 300x250 ads are implemented above the fold in a user-friendly way, the ads do not annoy, distract, or result in ad performance issues.
With the removal of this restriction, you still must be vigilant to ensure that their mobile site layouts do not cause ads to push the page content below the fold in such a way that may lead to accidental clicks. To ensure a good user experience, we still recommend the site content should be clear and accessible above the fold. See our optimization guide for the mobile Web for tips on where to place your ads.
As well as having a mobile-friendly site, it's important to provide a good user experience for your mobile audience. By focussing on your mobile site's design, content, and ad placements you could help to increase user engagement. In turn, this could lead to an increase in your mobile ad revenue in the long-term. For guidance on ad implementation best practices, please review our help center.
We hope you find this to be a positive update. Keep providing us with feedback!