iPhone 12 Pro camera shows black on 0.5x and 1x, but works on 2x and selfie mode

My iPhone 12 Pro's viewfinder won't show me anything - it is just a black screen. I can't take any photos on 0.5x or 1x, but I can on 2x and selfie mode. However, I can't actually see the photo I'm taking when I take it, it just shows black and saves the picture to my camera roll. In Snapchat and other third party apps the selfie camera works fine, but it won't let me switch to the back camera. In WhatsApp, though, I can switch to the back camera but I'm stuck at 2x and above.

Switching to the back camera in the native app is a challenge as well and only works some of the time. There was a short period of time where I could see very limited stuff (at a very low exposure I think - but I couldn't manually adjust it) on 0.5x, but 1x was the exact view as 0.5x, but it worked fine at 2x and selfie mode. Now it just won't work. I have dropped my phone and I think that it might be a hardware issue but if the 2x view and selfie camera are working fine and I can't see it then it suggests it's a software problem? I can also see the yellow boxes on the native app when faces are detected, but not the actual image. I noticed the issue and updated to iOS 18.3.1, but this hasn't helped - if anything made it worse.

I've tried everything - everything on the Apple website - and I've restarted the phone loads. My flashlight won't work either. I don't know what to do because repairs are expensive and if it's unnecessary I don't want to spend money on it. Advice please?

[Re-Titled by Moderator]