It looks like the message encourages users to update "to the latest software version, iOS 16.6." I wonder if their message is different to users on devices which no longer can be updated beyond iOS 15, like iPhone 7, 7 Plus, SE and so on.
That's the message they got in summer 2023 when iOS 16.6 was the most recent one.
why do you think devices out of support date got any message at all?