Ok, the problem is my camera's protective glass cover has wore down and now some dust has entered, causing the camera's output to become blurred. This is causing me a lot of issues currently, especially when I need to scan some QR code. For example, now I can't login to WhatsApp on my PC, cuz I need to scan their QR code with my phone.

What I want is, use another phone's camera instead of my phone's camera, just like the DroidCam functionality, where you use your phone's camera instead of your PC's camera. Are there any apps designed for this purpose?