Apple recently released iOS 15.2.1, and as is traditional, Apple has now stopped signing iOS 15.2, making downgrading to that version of iOS no longer possible.
Apple earlier this month released iOS 15.2.1. iOS 15.2.1 addresses an issue causing Messages sent through an iCloud Link not to load and it fixes a bug with third-party CarPlay apps not responding to input.
iOS 15.2 added Apple Music Voice Plan, a new subscription tier that provides access to music using Siri. This update also includes the App Privacy Report, new safety features for children and parents in Messages, and other features and bug fixes for your iPhone.
The new software can be downloaded on compatible devices over-the-air by going to “Settings” -> “General” -> “Software Update.”
Falling back to an older iOS build is often used by users that jailbreak their iPhones. Restoring an iPhone or iPad to a previous version of iOS can also sometimes be helpful for users who experience significant bugs after upgrading to the latest version of iOS.