The decision to leave the wi-fi and Bluetooth chips on iOS devices activated when disabled in Control Center was intended for convenience-i.e., to allow users to simply hit the button and not have to waste time fiddling around in settings when they want to use them again-but it did attract some attention as a security risk. It turned on/off WiFi and Bluetooth.
iOS 11, the fancy new version of Apple's OS that shipped just about two months before the launch of its latest line of expensive phones, introduced some changes to Control Center, its app which streamlines the annoying process of changing settings by putting the most commonly tweaked ones on a single swipe-up menu.
Apple has recently released iOS 11.2 Beta 3 to developers and it has been discovered that when users toggle WiFi/Bluetooth off from Control Center, a popup message will appear to explain that the features are only disabled until the next day, and that in the meantime WiFi/Bluetooth functionality will continue to exist for certain features/services/devices. Wi-Fi and Bluetooth still remain on in that disconnected state and will even reconnect under a few circumstances.
Unless you've been closely reading iOS 11 news the past weeks, you would probably never know that, which was the point of contention of some users. No where in Apple's on-device documentation actually informs them of that change.
Wi-Fi (Bluetooth) is reactivated using Control Center.
"Disconnecting Nearby Wi-Fi Until Tomorrow".
"Disconnecting Bluetooth Accessories Until Tomorrow. Bluetooth will continue to be available for Apple Watch, Apple Pencil, Personal Hotspot, and Handoff".