Samsung had announced that One UI 4, an OS skin based on the upcoming Android 12 version, would become available in a preview form last month. Now, a Samsung Galaxy S21 Ultra has been detected as running what could be this update on Geekbench 5. Therefore, the beta in question might be released soon.
https://www.notebookcheck.net/One-UI-4-allegedly-draws-near-with-the-sighting-of-a-Galaxy-S21-Ultra-on-new-software.557372.0.html