Same issue here. This should not be marked as solved as it is not solved/fixed
Got my Note 9 (AT&T 256GB version in bue) it was released in Aug last year. About a week ago I was trying to zoom in and noticed the image becomes very blurry once I hit the 2.0x zoom and there is a loud buzzing. Searched online and found this and a number of other forums with the same defect. Since day 1, my phone has been in a thick case and I have never dropped it (still looks brand new). Tried safe mode, still there, let the phone get cold, same issue, factory reset, same issue. Nothing I have tried works and make me feel that this is a defect considering how many other people have this issue. Frustrating that a critical function of the phone is useless.*
Well, I called AT&T since I am still under warranty and they sent a replacement. Got it today and without setting anything up (skipping all setup options), tried the camera and it has the same issue. The AT&T rep was very nice and they are taking the replacement bask as a "dead on arrival" device and sending another. I'll update when received.
In case anyone wants to see this first hand, I have uploaded 2 videos to YouTube, 1 of the phone in question where you can see it will not focus and buzzes very loudly and part 2 using my wife's Note 9 to show it starts at exactly 2.0x zoom. I'm just glad it happened now when the phone is still under warranty.
Video 1: https://youtu.be/2m5pjRZOBqI
Video 2: https://youtu.be/JFbBcjRwBKw
Update, the 2nd replacement works and does not have an issue. Had been over a week and the camera works as expected without any buzzing. If your does, get it replaced and text the replacement as soon as you get it.