White screen, shadows, and halo effect.

Ouch! You either had a liquid spill or condensation got into your display. At this point you really need to replace the display assembly MacBook Pro 13" Retina (Early 2015) Display Assembly here's the guide to put it in MacBook Pro （13英寸， 带有Retina显示屏， 2015早期） 显示组件更换 the lower grade B or C Stock screens are cheaper!

Taking the display apart to clean or replace the defuser sheets is not something I recommend for a first timer! To give you an idea here's the 15" screen breakdown MacBook Pro Retina Display Teardown as you can see its not easy and often you need to replace the sheets, sadly they are getting hard to find these days and you have the risk of breaking the screen in the process.