This is the second release candidate (RC) for iOS 17.1, following the third one from October 10, which replaced the second one from October 3.
The new RC has the build number 21B77, which is different from the previous RC, 21B74.
The reason for this exclusive update for the iPhone 15 devices is unknown. The previous RC fixed the issue of screen burn-in that some users reported. It is possible that this update will address the problem of devices shutting down overnight, which is another complaint from some users.
Developers who are part of the beta-testing program can download the latest builds from the Apple Developer Center or by updating their iPhone through the Settings app. After the developer versions are out, public beta versions will be available and can be accessed through the Apple Beta Software Program website
The first iOS 17.1 beta changed the Music app with a playlist of favorite songs, a star instead of a heart, more options to customize album art, and a new section for recommended tracks.
AirDrop over the internet has been introduced, as well as bank balance support in Apple Wallet for UK users. The update also has new flashlight icons for iPhone 14 and changes to ringtones.
The second beta added display options for Standby mode, some ring tone changes, and widget options.
AppleInsider and Apple strongly advise users not to install test operating systems or other beta or RC software on their main or important devices, as there is a small chance of issues that could cause data loss. Testers should use devices that are not essential and backup important data.