A bit of background, the iPhone 7 Plus has the largest battery of any of the iphones. I used to be able to go 1.5 to 2 days on a single charge prior to this update. I used the Settings --> Battery screen to determine that the top battery consuming app was RingCentral.
To test this, I ran for several days with the RingCentral app installed as normal and I did not use the app to make or receive any calls. In other words, I didn't use the app at all. My battery died quickly by afternoon. Then I turned 'background app refresh' off for RingCentral for a few days and as before I didn't use the app at all. With background refresh off, my battery life returned to normal.
Yesterday I was on the road and opened up the RingCentral app to make a call to the office. I forgot to close the app. By 1pm my battery was at 3%.
I created a support call and they simply said they would pass the suggestion onto engineering. This doesn't inspire confidence that this will be fixed.
I cannot have an app on my phone that takes it down in less than one business day.