I have an iPhone 8 (not the plus) and I'm running 12.1 OS. I take the phone off the charger in the morning and like 1-2 hours later I'm at like 10% battery life or less. I can't pin point when exactly this started happening, I feel like its only been a week or less. New things for me recently are: I downloaded 12.1 OS when it first came out, and I bought an Apple Watch for the first time about 2 weeks ago. When I go into settings---> battery, it looks like YouTube and Facebook are the two apps beating up my battery the most. They both seem to be using up battery in the background. I'm not sure that's the problem, as I haven't changed how I use these apps. Maybe a recent app update for both of them is causing me problems.