Dark Wide Strip on White screen

I don't see anything in the screenshot at the arrow. Everything looks like the same white except for the gray shadowing just below the menubar. Move the screenshot on your screen as I'm guessing the issue is with the LCD Panel on your built-in Display is bad. You can also connect an external display to see if you see the issue on it when the displays are mirrored.

Artifacts that are vertical are most often problems with the display itself.

This is because the display data are stored in memory and transmitted to the display as a list of horizontal slices, which are then "stacked" onto the screen to show the picture.