Samsung has started issuing Android 12 and One UI 4 to the Galaxy Z Flip3. The foldable handset will receive the OS upgrade as F711BXXU2BUKM with the December 2021 security patch.
https://www.notebookcheck.net/Samsung-releases-Android-12-and-One-UI-4-to-the-Galaxy-Z-Flip3.583259.0.html