
Interestingly, Samsung is still updating the Galaxy S21, S21+, and S21 Ultra to One UI 6 in some countries. For example, Korea received the One UI 6 update just a few hours back. However, Korean users are getting the November security patch with One UI 6, so the December update may take a while to reach all Galaxy S21 owners around the world.
As of December 14, the Galaxy S21 series' December update is available in some European countries. It comes with a firmware version ending in FWKB. It's a purely security-focused release, so it won't make any other changes or fix issues that some users may be facing on Android 14.
As always, you can download the new update on the phone using the Download and install option in its Settings » Software update menu or upgrade it using a Windows PC and firmware that is available in the SamMobile firmware library.