Whats with the crazy battery drain?!?

I have been using this app since it first came out. After the latest update my battery drains so fast its almost impossible to play anymore! I have the iPhone 7 with the latest version iOS as well as the app, turn off all other apps, kill wifi & Bluetooth, and darken the screen and the battery gets nerfed right before my eyes. Same thing is happening on my fiancées phone and we use different carriers (ATT & Verizon) so its not that either. Whatever it is causing this battery drain need to be fixed!!!

LLinOC about Pokémon GO, v1.31.0