So I had the exact same problem on my 2016 15” macbook pro and got it fixed for free.
If it was a 13” it would be covered by the https://support.apple.com/en-gb/13-inch-macbook-pro-display-backlight-service , if not read the rest of this.
In my case i started noticing this within one month of the repair of my keyboard under the https://support.apple.com/en-gb/keyboard-service-program-for-mac-notebooks
So, I went back to the mac service partner, said it started to appear after the repair, and they repaired it under the 3 months warranty given by the keyboard repair!
I’m almost sure you already experienced sticky keys on your keyboard or double typing of some keys, if you didn’t it will happen soon, and i think they will only repair it within 4 years from the purchase date (btw i bought my Macbook pro second handed in Malaysia and i don’t have the proof of purchase but it was serviced without problems in Portugal).
What i suggest if you do not have warranty is to go to a service center and complain first about the keyboard.[br]
They will replace it under the Keyboard Service Program available for several macbooks and after some time go back and complain about the screen and see what happens!
PS with my keyboard replacement i also got a new battery as it is glued to the top case :D
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=== Update (07/13/2019) ===
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I have the exact same problem on a late 2016 Macbook pro 15” touch bar but only after it went to replace the keyboard!
So I had the exact same problem on my 2016 15” macbook pro and got it fixed for free.
If it was a 13” it would be covered by the https://support.apple.com/en-gb/13-inch-macbook-pro-display-backlight-service , if not read the rest of this.
In my case i started noticing this within one month of the repair of my keyboard under the https://support.apple.com/en-gb/keyboard-service-program-for-mac-notebooks
So, I went back to the mac service partner, said it started to appear after the repair, and they repaired it under the 3 months warranty given by the keyboard repair!
I’m almost sure you already experienced sticky keys on your keyboard or double typing of some keys, if you didn’t it will happen soon, and i think they will only repair it within 4 years from the purchase date (btw i bought my Macbook pro second handed in Malaysia and i don’t have the proof of purchase but it was serviced without problems in Portugal).
What i suggest if you do not have warranty is to go to a service center and complain first about the keyboard.[br]
They will replace it under the Keyboard Service Program available for several macbooks and after some time go back and complain about the screen and see what happens!
PS with my keyboard replacement i also got a new battery as it is glued to the top case :D