Following the release of iOS 13.2.3 on November 18, Apple has stopped signing iOS 13.2.2, which means downgrading to this version of iOS is no longer possible. 

iOS 13.2.2 was a bug fix update that addressed an issue that caused some apps to quit unexpectedly in the background, which led to more frequent than normal refresh times for apps like Safari, YouTube, and more. 

Apple routinely stops signing older versions of software updates after new releases come out in order to encourage customers to keep their operating systems up to date. 

iOS 13.2.3 is the current publicly available version of iOS, and is another bug fix update that includes fixes for search, the Messages apps, background downloading, Mail, and more. 

Developers and public beta testers can also download iOS 13.3, an upcoming update that introduces Communication Limits for Screen Time and a handful of other tweaks and changes.

Source: Macrumors