BVCam is a third party app. It was not installed by the update. You either downloaded it from the App Store, or you accidentally restored your phone from a backup that had it installed. Either way, you can just delete it.
BVCAM by yanxuan CHEN
https://itunes.apple.com/us/app/bvcam/id1000307377?mt=8
iPhone User Guide for iOS 11 by Apple Inc.
https://itunes.apple.com/us/book/iphone-user-guide-for-ios-11/id1263310224?mt=11