White vertical line after "bright"

Hi, I would like to know what are these lines on the phone.

It only happens when im watching a video with black screen and I increase or decrease de volume or double tap to skip or rewind 10 seconds (both create a "light"), otherwise the screen display is normal. Here are the images to help understand.

Is this software and most likely will be updated? Or can be hardware?

There are 3 photos, one normal just watching the video, one changing volume, and other one after tapping to skip 10 seconds of the video.

Hope someone can help. Thanks!