iOS 14 on my iPhone 6s

That doesn't look good. Try the following-

1. Try and Force ReStart Your iPhone as instructed in this article by Apple ➔ How to Force ReStart your iPhone. If that does not work then -
2. If none of the above works then please contact ➔ Apple Support

Axel F.

Try a forced restart, but if that doesn't cure this, you have a hardware issue and the phone will need to be seen by Apple or an Apple Authorized Service provider.

To force restart: Press and hold BOTH the power and home buttons at the SAME time (keep holding past the swipe to power off) until you see the Apple Logo, then let go. Once you sign back in, see if the camera function is normal.