iPhone 8 Plus camera

The back glass of my iPhone 8 Plus was cracked already , then it fell a second time and the back cracked a bit more. When I got my phone the next morning I realized that my flashlight stopped working. Also my back camera only displays a black screen. The front selfie side works only. What I find weird is that my back camera only works on Instagram and Facebook messenger, but it only shows the camera zoomed in. What is the problem? Really want to fix this issue soon