Macbook blurry lines

Hi guys, i recently brought a macbook pro 2019 touchbar brand new in the packaging still from ebay i only brought it bc it was brand new and it was cheaper than online. However my mac started showing these lines all across the screen and i havent dropped it or broken it because ive been very careful as im using it for university. I took it to apple and they said it isnt under warranty anymore bc its the 2019 model. Does anyone have any ideas as to what this could be ?