Apple iOS 14.5 code suggests security updates may be offered separately in the future

Fairly often, users of older iPhones or iPads will forgo new iOS downloads for fear of making their gadgets run slower, since these updates are always catered around the latest lines of devices. While Apple made sure that iPhones from the 6s model and newer would be able to use iOS 14, it is well known that they are not the focus of the updates, and some of the upgrades may not be able to improve functionality on older models, unnecessarily clogging up space.
However, updates focused solely on improving security are light and wouldn't change your operating system, only patch existing issues and enhance data safety online. For example, the 14.4.1 update was simply released to fix a single security flaw in WebKit (Apple's internally developed browser engine for Safari).
The code suggesting all this is not something discussed or confirmed by Apple, it's just there as a potential idea. Not all of Apple's ideas have come to fruition in the past, but it's good to know there's at least the possibility of such a convenient security patch delivery method in the future.
On a side note, Apple does not disclose security issues until they've been investigated internally and patches are sent out. Any recent releases and updates can be easily found on the Apple security updates page.