Samsung Galaxy S9 and Samsung Galaxy S9+ smartphones will no longer receive software updates. Flagships of early 2018 are now SamsungIt has been removed from the list of devices eligible for security updates.
By the way Galaxy S10 series has moved from monthly updates to quarterly updates as they are now over 3 years old.
The Galaxy S9 series follows the path of its predecessors. In early 2021, Samsung Galaxy S8 completely delisted it downgraded the S9 from monthly security updates to quarterly security updates and same thing a year ago Galaxy S7 Happened to their phones too.
The last major update of the Galaxy S9 series was received in late 2020. OneUI 2.5 it was in the package.