Same issue with the iso 14.2 on a 6s. If I am actively using Safari, mail, Facebook etc app open, then I can watch the battery drain by each percent. Within 2 mins, I have seen about 10-15% battery drop, while using the app. If it just the Home Screen a can still watch the battery percentage drop but not as significantly. Placing my phone facedown and not using it, I will still see a noticeable drop in battery life after a few hours. I have the background refresher off and only allow mail to update when I open the app along with other battery saving settings set up.