Bright lights reflecting off the sensor when you are taking photos of bright lights at night are called lens flare and VERY normal. Before you took the photo, you could plainly see the flares on your iPhone screen. To avoid or eliminate this angle the phone differently from the scene, which will reduce or eliminate these naturally occurring flares.
Here is an example of a photo with lens flare and one where angling the phone differently removed them.
A photo with lens flare:
Without changing my position, but by simply angling the phone differently relative to the scene, the flares were eliminated: