Hi, everyone!
I just updated iOS 11.1 Public Beta 1 to iOS 11.1 Public Beta 2 and it simply solved the problems which cause iPhone battery drained up so fast as discussed in this forum.
Everything just back to normal including the assistive touch which said in previous beta version could be the 'bugs' causing the iPhone battery drained so fast, well, we can use it again.
Plus, there's some others improvements, like 3D touch multitaskings and SOS emergency.
just try it, it is really the solution for iOS 11.1 public beta 1.