When Apple released iOS 15 last fall, the company guaranteed that users who did not want to upgrade from iOS 14 would still receive essential security upgrades.
That choice appears to have vanished, as Apple’s home advisor stated this week that it has always intended to migrate all iOS 14 users to iOS 15.
The most recent security update for iOS 14—iOS 14.8.1 (together with iPadOS 14.8.1)—was released in October, but 9to5Mac reported this week that iOS 14 users could no longer update to that version.
15.2.1 is the only choice that appears presently. Apple later acknowledged to Ars Technica that this was done on purpose and that the ongoing security updates for iOS 14 were only intended as a short grace period.
Apple made no mention of this when it first announced and released iOS15.
In reality, as of this writing, the features list for iOS 15 still states (at the bottom) that iOS 14 users can still receive security updates, with no mention of a time limit.
Apple, on the other hand, provides the most recent macOS security patches for the most recent version of the OS—Monterey—along with the prior two, Big Sur and Catalina. Catalina predates iOS 14 by a year.
The sole distinction between these two iOS versions is that iOS 15 is backward compatible with all iOS 14 devices, therefore there are no hardware issues.