”iOS 10.2.1
iOS 10.2.1 includes bug fixes and improves the security of your iPhone or iPad.
It also improves power management during peak workloads to avoid unexpected shutdowns on iPhone.
For information on the security content of Apple software updates, please visit this website: https://support.apple.com/HT201222 ”
They mention it, and an investigative journalist could have dug deeper based on it, but as is, that’s fairly vague.
And my understanding is that there is no explicit mention in the changelog, just an opaque mention of new power management feature. But again, no one reads changelogs and the folks at Apple know that.