So, I too have now received Android 9 (Pie) on my ATT 128gb variant yesterday. So far, the camera has not acted up. The camera app is different, and maybe at one point I experienced a little stuttering while using the camera for a regular photo, but other than that, I haven't had any other issues. We'll have to see if this lasts, or if this is just temporary.
Still no issues with the camera since T-Mobile pushed out the ARL1 update to my Note 9 weeks ago and I have used it a lot since then. This awesome phone now works as desired. Thank you Samsung for addressing that annoying bug!
Follow up - So I can with 100% confidence say the issue is fixed with 1Ui and Pie (running CSAA on ATT Note9 512gb). I ran the beta updates until the official update for the ATT model was released last week and I havent had a single issue with the camera. Everything seems to work well on the phone now, with the only issue that I've seen was my keypad disappeared during a call. Happened once and haven't seen it do that since. I FINALLY feel like I have the phone I paid for. A perfect phone (at least for what I need and want).
Hopefully everyone else will get theres going as well. Best of luck everyone!