Apple has stopped the signing of iOS 17.2, which means it’s no longer possible to officially downgrade to the earlier version.
The ending of support for iOS 17.2 is not strange as Apple does ‘retire’ older versions when newer ones come along. This practice is done to encourage users to keep their devices updated to the latest version for security purposes. Older versions might still have bugs and critical issues that could lead to data loss and others.

iOS 17.2 had major features such as Apple Music updates, Messages, spatial video recording for the iPhone 15 Pro, and the Journal app, among others. Bug fixes were not detailed in iOS 17.2.1. As of today, iPhone users will no longer be able to downgrade to a lower version as far as official channels are concerned.
iOS 17.3 is under testing phase and is expected to release this month.