Apple has stopped signing iOS 15.2 to its servers. This means that it is no longer possible to install this particular version, either as an update or as a rollback.
It is no longer possible to install iOS 15.2
The final version of iOS 15.2 was released on December 13. This update brought the opportunity to have Apple Music Voice and changes for Privacy, Apple ID, Camera, App, CarPlay, along with various improvements and bug fixes. It is therefore no longer possible to install this specific version of iOS.
Apple then released iOS 15.2.1, this dates back to January 12. This was a small update to fix bugs with CarPlay and the Messages app, as well as to fix a flaw in HomeKit. To date, this is the only version of iOS that can be installed.
The next version will be iOS 15.3. It is currently available in beta from developers and public testers. We are in the second beta, it was released last week. Apple does not yet say when it will be available in stable version for all users. This version is surprising for the moment because it does not bring any particular novelty, although it is an x.3 update. But who knows, maybe we’ll have some surprises between now and the final version.