Chosen Solution
I haven’t used my macbook for awhile, and when i open it its just like that
Humidity did you in! This looks like mold growing on inside surface of the cover glass/displays top surface or the defusing sheets behind. You’ll need to take the display apart to try to clean it. Follow this guide to get the display assembly off MacBook Pro 13" Unibody Mid 2012 Display Replacement and then pickup at Step 15 here MacBook Pro 13" Unibody Mid 2009 LCD Replacement Hopefully the staining is on the top side.
