I think MR got tired of some people saying to stop posting articles informing about Apple no longer signing older firmware/OS versions...
Aside from iOS 14.8, iOS 12.5.4 also no longer signed...
There's a difference between "this random 1.2.3 release is no longer signed" and "The latest version of iOS 14, which Apple promised to keep supporting, is no longer signed". That's why I thought this was topic-worthy.
Your version is just slightly too old, the capability for the Settings app to provide a version choice when updating was added in 14.5.
This is a new thing so we don't really know how it will work, we're going to have to wait and see if Apple starts signing a version of iOS 14 again in the future.
This is 100% correct.
Before iOS 14.5, the Settings app was configured to show the newest available update and that's all it would offer. In 14.5, they changed it to offer the newest release of iOS 14 with an "Upgrade to iOS 15" button at the bottom of the screen.
All my devices I use regularly were on iOS 14.7. When iOS 14.8 came out, Software Update picked it up and offered to install it.
I have an iPad 2017 I don't use often. It was still running iOS 14.3. When I went into Software Update, the only available option was iOS 15. There was no way to update to 14.8 over the air because Apple hadn't built the option yet.
I updated to iOS 15, didn't like the new Home Screen grid at all, then used an IPSW to downgrade it to 14.8.