Z flip

I had purchased a Samsung Galaxy Z Flip 4 and was told that I can flip the device a 100 times a day for 5 years without experiencing any issues with the device however within the first 6 months the screen when dim. I have not even flipped the device as much as was advised and my device has now a lcd or white line through the middle of the screen which is causing the entire screen to dim. I then received the device again and the same issue has occurred again where I flipped the screen and I dont even flip it anywhere close to a 100 times a day and the screen when completely black and covered in ink.