Macbook Pro 15" 2018 Screen Issue- thoughts?

I was recently gifted a Macbook from work (ceasing business). The Macbook works fine - however there is an issue with the screen where there is a slight flickering, and odd colours (pinkish/green hues). Weirdly this only kicks in a few seconds after boot up and only really seems to effect whitish sections of the screen.

Initially I thought, well its just new screen time, but I wonder if the cable is simply slightly off, or damaged? Is there anything I can check? Also is the cable a separate item that can be replaced? Or simply a new complete screen. Apple Diagnostics (D on start up) states all is well.