I came here to say: NO. The Flexgate has not been fixed on the 2019 15” Model. I have the 15” Model with Core i9 and today I opened the lid and saw the issue. At first I tought of some mac os glitching but no the error stayed on boot. I then plugged in an external Screen and the issue only showed on the integrated Screen. So I can point out the GPU. Then I slowly closed the Macbook and in an nearly closed angle, the Graphic Issues are gone.
So my problem is: all Apple-Stores have closed now because of COVID19. I hope they can help my on telephone, when they call me on monday. I am 100% doing some extra insurance or apple care+ for that Macbook. I am really lucky as it happend like 3-4 Month before the 1-Year Warranty ends.
Video (german): https://twitter.com/deniz_koekden/status...