After update 11.4 ios my iPhone 6s getting battery drain fast

I have the same issue with my 6S. It was fine before the update. And my battery health is at 90% yet I just watched my battery % drop from 50% to 20% in a matter of minutes while not using it. I’ve looked through all the settings and can’t see anything I’ve previously had turned off turn back on with this new update in regards to saving battery life. Whatever it is that’s causing it they need to fix it ASAP