iPhone 6s Screen cracked despite not dropping it

I recently replaced my iPhone 6S screen after I dropped it with a new screen from iFixit 3 weeks ago. I’ve had a few imperfections like the auto-brightness feature not working but nothing too concerning. A couple nights ago I found a slight scratch slightly to the left in my screen even though I hadn’t mishandled it at all. It was enough to be felt with a fingernail but it was too small for me to care about it that much.

When I found it the next morning, the screen had a fracture in it with both ends of it meeting on the left side in a backwards C-shape. Since then I have noticed a couple scratches similar in size to the first one. I did not use a screen protector, but I don’t remember doing anything that could scratch the screen like that. Might I have to replace the screen again or might I want to install a screen protector and be fine after that?

Image of the cracked screen. It is hard to see because of poor camera quality