Samsung Electronics stopped supporting security updates for the Galaxy A series, which was released four years ago.
The Galaxy A series, which has been discontinued, are sold in January 2017: the Galaxy J3 Pro, the Galaxy A7 (2017), the Galaxy A5 (2017), and the Galaxy A3 (2017).
In addition, Samsung Electronics moved the 2018 Galaxy A8 from monthly updates to quarterly updates, and added the Galaxy A02 and Galaxy M12 to the quarterly update list.
Three of the latest smartphones, Galaxy S21, Galaxy S21 Plus, and Galaxy S21 Ultra, have been added to the monthly update. The Galaxy S21 series will receive an operating system (OS) upgrade three times in the future.