replacement phone

Less than a year ago, my old iphone x broke so I paid an out of warranty price for a replacement iphone x. Then, less than a year later, that phone stopped working, I did nothing wrong and it seems to be an internal motherboard problem. Why is it that when I went to the store, they said I would have to pay full price for a new iphone? Isn't it apple's job to provide a good working replacement and not one that will stop working in less than a year?

Also the phone purchased less than a year ago said OW (one-year warranty).