While night shooting, doing Astro photography, with the Nikon Z 9 at high ISOs and low shutter speeds, one of my two Nikon Z 9s showed very visible and noticeable noise/static in both the LCD and viewfinder. It begins at about 1/30 sec and gets progressively worse at slower shutter speeds, becoming prominent enough to make viewing the subject nearly impossible, particularly if I've also set the camera to the "Warm Display Colors" setting for night shooting. While my other Z9 to a lesser extent displays the same problem, I tested a Z 8, which does not display that problem even when set at "Bulb" and an ISO of 25,600. I am wondering if others have experienced this issue. Both cameras were recently returned to me from Nikon following maintenance and repair work and I assumed, since part of the process is supposed to be a thorough examination of the sensor, that the problem would have been identified and fixed. I've contacted Nikon about the problem and I'm awaiting a reply. Have any Z 9 users experienced the same problem? I'm wondering if it's normal at those settings or if I have a sensor problem since the Z 8 does not have the same problem. I first noticed it a couple months ago while attempting to shoot the Aurora Borealis in Grand Teton National Park. While it's only noticeable at night, or with the lens cap on the lens during the day, it most assuredly is also occurring in daylight, and since I will shoot at those lower shutter speeds when shooting landscapes, I'm concerned about the noise effect on the photos. I should note that the problem shows up even at the camera's native ISO of 64 and at 1/30 sec and so ISO would seem not to be the the primary issue. The forum's thoughts would be appreciated.