'Seamless updates', first introduced back in 2016 and arrived on every Google Pixel phone, allows for firmware updates to be installed to a secondary partition while the phone remains in use. This eliminates downtime between firmware updates to a single reboot, after which the secondary partition becomes the main one and the update has already completed. This also acts as a failsafe in case an update goes wrong – the system can fall back on the previous partition. Update notification on a Samsung Galaxy S21 Ultra Google has backed off on this requirement since it’s no longer in...
Source: https://www.gsmarena.com/seamless_updates_is_a_great_android_feature_that_the_samsung_galaxy_s21_ultra_still_doesnt_have-news-47389.php
