MacBook PRO white fading border - me too - SOLVED
I wanted to reply to https://discussions.apple.com/thread/7960425 and https://discussions.apple.com/thread/251692684 as I had exactly this issue this week.
And also for me none of the googled solutions worked for me, so based on the experience in the last thread, i went patient. Switched off my MacBook and checked the issue every few hours.
And indeed it very slowly disappeared and is gone now. It took about 18 hours on my MacBook.
One thing (not sure if relevant or not) is that when it happened my MacBook was very cold (left in a unheated room with windows open, temp dropped to below 10°C. THe recovery was done at normal room temperature.
Anyway if you have this issue, do turn patient, do nothing, just wait and hopefully it also disappears by itself.
MacBook Pro 15″, macOS 10.15