After seeing the new update for Galaxy S21 Ultra, you can say it has become old device now. Samsung released October security patch for this flagship model, when we are near to December. It is only 260MB firmware that doesn’t bring anything in it.
The new software G998NKSS4EWK2 is rolling out in India with minor bug fixes and device stability improvements. There is no news yet on One UI 6 for the smartphone.