https://www.bleepingcomputer.com/news/apple/apples-first-rapid-security-response-patch-fails-to-install-on-iphones/

Apple has launched the first Rapid Security Response (RSR) patches for iOS 16.4.1 and macOS 13.3.1 devices, with some users having issues installing them on their iPhones.

As the company describes in a recently published support document, RSR patches are small-sized updates that target the iPhone, iPad, and Mac platforms and patch security issues between major software updates.