For many reasons, users might choose not to opt into any of Apple’s latest iOS update, one of the major being impacted slow performance on older iPhones. Apple itself admitted to this in December.counteract problems in ageing lithium-ion batteries”; it’s clear that their strategy is to back their customers into a corner, rather than actually giving them an incentive to upgrade.
Soon, iPhone 5 users will have no choice but to succumb to the dreaded system update.
Additionally, a bug that prevents devices as old as the iPhone 4S and first-generation iPad mini from using GPS, and prevents it from gauging the correct date and time, will be fixed.
So, unfortunately, if you’re one of the 9% of iOS device users who run software earlier than iOS 12, you’re going to have to press the “Update Now” button within the next week.