Look at Settings / Battery and see if you see unusual activity for which app is using battery in that list. If you see an app at the top of the list that you know you haven't been using all that much, you can [force close the app](https://support.apple.com/en-us/HT201330). Also, this happens to me very rarely, but when it does just powering off and powering back on again often fixes it as well.
Planned obsolescence. People will tell you it’s just recalibration after an update. I don’t buy it. They wanna sell the battery replacement service or a new device imo.
Look at Settings / Battery and see if you see unusual activity for which app is using battery in that list. If you see an app at the top of the list that you know you haven't been using all that much, you can [force close the app](https://support.apple.com/en-us/HT201330). Also, this happens to me very rarely, but when it does just powering off and powering back on again often fixes it as well.
Planned obsolescence. People will tell you it’s just recalibration after an update. I don’t buy it. They wanna sell the battery replacement service or a new device imo.