A user said that her display turned black when she opens the camera app, adding that she has been facing this problem since she has updated her iPhone to iOS version 11.4. To this Apple Support replied, “Thanks for reaching out to us about the camera. That's not normal behavior, so you are right to be concerned. We're ready to team up and solve this together. Work through the steps in this link, and let us know the results. Thanks!”.
Another user posted a video on twitter that showed jittery movement when the camera app is opened. He said he updated his iPhone to iOS 11.4 and has been facing problem since the update, doubting that the problem will be rectified soon.
Last week, Several iPhone users expressed their problems on Apple forum regarding faster battery drainage with the latest update. While some posted solutions on the Apple forum, many rolled back to the previous version of iOS. Apple released the stable version of its iOS 11.4 in May with support for HomePod stereo pairs and wireless multi-room audio system using AirPlay 2. Bug fixes and improvements came in too.
Apparently, every iOS device that has been updated to the 11.4 version has been affected by the battery drainage issue. According to GSMarena, while switching off the Wi-Fi worked for some users, connecting to a 2.4GHz Wi-Fi network (instead of 5GHz) helped several others save battery. There is a third group of users who have switched back to iOS 11.3.1 to keep their phones running for longer hours before they plug-in the charger.
iOS 11.3 was a major update because it came after the iPhone maker faced flak over the revelation that it was purposefully slowing down iPhones to save battery life. iOS 11.3 added new features to show battery health of an iPhone or iPad and recommend if a battery needs to be serviced.