I have a Z camera and am miffed that so many AF-D lenses do not work. Now the min reason I have for owning a Z camera is weight. I certainly would use a FTZ that worked using AF-D lenses. The Nikon Z50MM makes a joke of weight savings compared to my 50MM f1.8D
Could it be light reflecting inside the lens? Some of my lenses have done this. Back in film days I used a Quantaray 70-300. I took a shot f the full moon and ended up with a half dozen moons as it reflected all over inside the lens.