If you’ve updated to Apple’s new iOS 11, you might have played around with the new Control Center. You also might think that toggling Bluetooth and WiFi “off” in the Center might actually, you know, turn them off. Turns out, you’d be wrong. As noted over at Motherboard, hitting these buttons really only disconnects you from any WiFi or Bluetooth devices you might be connected to.
Source: iOS 11’s Control Center buttons don’t fully turn off Bluetooth or WiFi