In conjunction with iOS 9.3.6, the software in question brought important fixes to GPS, something that came to fix the inaccuracy of the feature, something that also applies to the iPad 4 LTE, iPad mini iPad 2 and iPad 3.
By powering older devices with newer versions of iOS, Apple has shown that it does not intend to “jump ship” if serious problems do arise (even with older devices).
In the official statement of apple we can read something like:
Beginning at 12:00 UTC on November 3, 2019, iPhone 5 will require an iOS update to maintain accurate GPS location and continue to use functions that depend on the correct date and time, including App Store, iCloud, Email and web browsing.
This is due to the GPS time override issue that began affecting third-party GPS-enabled products on April 6, 2019.
Affected Apple devices will not be affected until shortly before 12:00 UTC on November 3, 2019.
If you update iPhone 5 by November 3, 2019, you will need to back up and restore iOS 10.3.4 using a Mac or PC – this is because OTA software updates and iCloud backup will no longer work.
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To make sure you’re on the latest version of iOS, just go to Settings> General> Software Update.
Source: support.apple