Same here. I followed all the recommendations to fix it (trying different apps, users, utilities, etc), afterwards I called apple support and after 40min on the phone they told me that this specific computer was designed to have bad quality camera under non-natural light. They said it will only look good during day light and if I'm in a room with lots of natural light. Unbelievable! They said there's nothing they can do from their side to fix it because is not a software issue or a bug. Their only suggestion to "fix it" was that I only use the camera by day in a bright room, I'm speechless!
Unfortunately I can't return the computer because it has been a month since I bought it, but if you are still on time to return it I highly recommend to do so since apple doesn't have any solution and apparently they are not willing to do anything to compensate this fault.
Shame on apple! After 20 years of using mac I'm planning to leave it once and for all.