Yup, just have a look at the 'Similar Threads' at the bottom of this page, Threads about iPhone 6 lens flare dating back over 3 years!I have photos showing this is not new nor unique to the X nor unique to Apple. The iPhone 5C, 6S, 7 Plus, X, Huawei Mate 9 and the Samsung S8 all do this to some extent or other. I have or have access to all these phones and they all do it.
Don't know where these people complaining have been for the last 3 years, probably not taking photos on phone cameras one can presume!
I'd like to hear what the solution to this inherent 'issue' could be..?