Background Refresh Is Turned On
Background refreshing allows apps to automatically refresh their data even when you’re not using them. For some users, this isn’t a problem, but for others with a lot of active apps, it can be a huge battery drain – and it’s rarely necessary unless you have a super important app that needs to always stay updated.
In Settings, you can go to General and choose the Background Refresh section to turn all background refreshing off, or choose which particular apps can do this. Try using it as little as possible.