Apple was testing Rapid Security Response on beta versions previously, and now finally uses those for iOS/iPadOS 16.4.1 and macOS Ventura 13.3.1.
Apple did not provide security contents of the update yet.
Apple Support: About Rapid Security Responses for iOS, iPadOS, and macOS
Developer:Business as usual.
QA engineer:Check apps for regressions.
PM/DM:Business as usual.