Back camera issue.

I have an iPhone 8 Plus When I launch the camera app a faded horizontal blue line with a length of about 1cm is visible on the middle of the screen, When the background is white it’s visible more clearly. Only the camera app shows this.

I recorded a time lapse yesterday morning and got the issue evening on the same day.

I left the phone to record the time lapse, after an hour or so it had stopped recording and the screen had turned off (hadn’t shut down completely) due to the temperature warning,

Is this issue caused by the temperature? I’m really looking forward to some answers...