As of yesterday, when the fourth developer beta of iOS 9 was issued to testers, those running a prerelease version of the operating system can no longer leave app reviews in the App Store. Negative app reviews left by beta testers is a perennial problem for app developers (as highlighted well in this post over on MacStories), and it’s nice to see Apple taking steps to fix it even though OS X El Capitan beta testers can still leave app reviews as of this writing.
Source: Apple disables App Store reviews from devices running iOS 9 betas | Ars Technica