Press around on the screen as well around all the edges, and gently on the screen itself towards the center on the top side maybe 2 inches down from the bezel, also try pressing firmly on the plastic above the keyboard.
If its a cable issue sometimes pressing will cause the issue to go away/get worse and tell you that it maybe a cable issue/loose connection.
As stated could be the screen itself.
If your machine is the one with a dedicated graphics card, chances are buying a new laptop may be the better option, unfortunately in my experience they seem somewhat difficult to source, and when I have found them they’re quite expensive ~$250
JVG if you would like to bring it to my shop this week in Clifton Park, I’ll take a look at it and see whats going on. PM me if you’d like.