When Apple learns how to bend the laws of physics as it relates to digital images, that would be mind blowing.
If I take a photo that is important to me and there are flares, I have an Adobe Cloud membership, which gives me access to Photoshop applications. I use post processing software to fix things if its important.
Otherwise, you do the best you can in angling your camera better. Apple can't fix something that no one else on the planet has fixed either. And this is true with cameras and lenses costing far more than an iPhone costs. The expectation Apple can fix something they simply cannot is what is unrealistic. Whether you want to hear that or not.
And yes, I saw the image with the sign. Had I had the same camera in my hands, I could have taken the photo without the reverse flare. I've done it successfully multiple times. One has to learn how to use the camera. Real photographers NEVER blame the camera. They blame themselves for not using the equipment properly.
Question for you. How many camera systems do you now or have you owned previously that have the ability to take photos of bright lights in low lit situations, without requiring you to place the camera on a tripod? I'm going to guess the answer is none. You how have a system which can take photos and videos in low light like you've never had the ability to do on other systems. These flares are normal. Some can be avoided. Some not so easily. Invest in some good post processing software.