The latest update for the OnePlus 9 and OnePlus 9 Pro can be identified by version number ColorOS 11.2.A.12. As this is a ColorOS update, it is currently rolling out in China. Regarding changes, it bumps the safety level to October 2021. Also, the package resolves some known issues thus, improving the system stability. Moreover, the application response is now stable. If you are using the OnePlus 9 Pro, then your fingerprint unlocking experience is now optimized.
Changelog
OnePlus 9
System
Upgrade Android security patch to 2021.10
Improved System stability and fix known issues
Alarm clock
Fixed The problem that the application does not respond in some scenarios
OnePlus 9 Pro
System
Optimization Fingerprint unlocking experience
Upgrade Android security patch to 2021.10
Improved System stability and fix known issues
Alarm clock
Fixed The problem that the application does not respond in some scenarios
As always, the package will initially roll out to a limited number of users. A border rollout will follow after ensuring that there are no critical bugs.
If you own any of the duos, a notification will spring up on the device. Alternatively, you can track the update manually by heading to Settings > Software updates > Check for the updates > Download and install.