I know it has been seen on other iPhones because I have examples of it on other iPhones in the link I’ve included, and because every camera ever made over the past 150 years will exhibit lens flare when there is a bright light source in the image, or just outside of the image. Please click on this link and see examples of it on other iPhones, Android phones, and $50,000 professional cameras→iPhone Camera Lens Flare and Reflections - Apple Community. PLEASE review this; you will see examples from the following iPhones: 6, 7, 7+, 8+, X, XS, 11 Pro Max, then Samsung Galaxy S21, DJI Drone, Pixel 3, Pixel 5, Pixel 6, Panasonic video camera, Samsung Galaxy Note, Samsung Galaxy S20, Canon DSLR, ARRI Alexa Mini ($50,000 cinema digital camera with $10,000+ lens).
But please click on the link and review it before saying it doesn’t happen on other iPhones.
If you haven’t noticed it perhaps you didn’t take photos with bright light sources in them in the past, or you just didn’t notice.