I noticed a strange issue during my usage of Android Pie beta. When turning off the screen and locking the device, the display was turning red for a fraction of a second. Have you experienced it as well? Now, I rolled back to Oreo in expectation of the official release of the Pie and I do not observe this problem. Can it be from a bug in the Pie firmware. If it is, the situation will be very discouraging. I do not know what the HMD developers are doing.