Not exactly a solution for already affected device but I strongly believe that the cause of the flickering may be an issue with the socket/extension/charger that I have been using. And if you are getting a replacement, this could save your new device.
I realized this may be the issue after seeing some comments whereby others solved the problem by moving rooms they work in. And it made sense because I had the flickering screen issue for my original device, then my replacement device.
And now, I am borrowing my sister's device and the problem is only now occurring. (It worked fine under my sister for 1 year +)
So highly suggest to change as much power accessory/gear for your new device to prevent the problem from occurring.