macOS Rapid Security Response 13.3 (a) is applied to the Mac automatically upon restart.
This is the second RSR that Apple has released for a macOS Beta. The first RSR release did not add any new features, with Apple instead using the launch as a test to make sure it is functional before it is deployed for an actual security update. Today's update may also be launching in a test capacity, and it is unclear if it includes any actual security fixes.
Rapid Security Response is an iOS 16 and macOS Ventura feature released as part of those updates.
