https://wccftech.com/samsung-continues-impress-with-timely-updates-for-the-smartphones/

Samsung started rolling out the April security patch to the Galaxy S21 series and many other devices before April even started, with my device getting the update on 31st March, earlier this year. But as we are all aware, the updates happen in stages. Samsung is continuing the impressive streak as the company has launched 4 builds in total, spanning across the Galaxy S21 series and Galaxy Note 20 Ultra.

With that said, the updates for the T-Mobile Galaxy S21 series and the unlocked variant of the Galaxy Note 20 Ultra. If you own any of these phones, the update notification should hit you pretty soon, and you should be able to download it with ease. Still, you can go to Settings > Software Update and check whether you have received the update or not.