According to Sammobile, the latest software update for Samsung Galaxy A21s carries firmware version A217MUBU8CUK3. It is currently rolling out in Latin American markets and should expand to other regions over the next few days. Samsung Galaxy Tab A 10.1 (2019) is also receiving the December 2021 security patch. This one is reportedly rolling out in Ecuador and Peru with the firmware version T515XXS8CUL2. It is a minor security patch update. Therefore, you should not expect anything like new features, performance improvements, or changes to the user interface.
Samsung Galaxy A21s and Galaxy Tab A 10.1 (2019) users in the specified regions have started picking up the new update. Those who are still in the queue should manually check for the updates via Settings » Software updates and then tap on Download and install, if an update is available. If not, then check back again after a couple of days. Samsung released the Galaxy A21s last year running Android 10 OS. Thanks to a major OS upgrade, the device is now running on One UI 3.1 skin, based on Android 12. Galaxy Tab A 10.1 (2019) is a comparatively older device, which came pre-installed with Android 9 Pie. It has already received two major OS upgrades. The Galaxy A21s is expected to receive the Android 12-based One UI 4.0 update in the first half of next year. However, there is no information about the Android 12 upgrade for Galaxy Tab A 10.1 (2019). [source 1
