Purple lines and blocks all over the display

There was purple lines all over my screen and the side of my screen was flickering. Then black and purple blocks started appearing on my screen. Now, my screen is completely black. I have a 2020 MacBook and went to the Apple Store and was told that there is no damage but it's just a hardware issue. They said the repair will cost $570. Very frustrating because we decided against purchasing Apple care because we hadn't had any problems with past MacBooks. Why could this have happened?