I bought a Z50 with the two kit lenses last summer and shoot on Manual setting (single shot), and have U1 set to take 2 bracketed shots (metered and minus 2 stops), with U2 set to 3 shots (metered and plus and minus 2 stops). These work well for the situations in which I use the camera. However, the camera randomly shoots an extra shot on any of these settings (i.e. I just tried it using the U2 3 bracket setting and I got 4 shots, yesterday on the M single shot I got 2 images). Most of the time the camera follows the settings, but often it takes an extra shot. This can happen in the middle of shooting a series of images.
This is not a problem in so far as it always shoots what is has been set to and adds on a shot, so I don't miss out on what I'm trying to get. But it adds extra files to my memory card, and it is frankly disconcerting never knowing how it will react.
I told Nikon UK about this, gave them a list of the settings I use, but they didnt spot anything wrong with those, and suggested I make sure I was using the latest firmeware (I was but reset that just in case). After sending them a short video showing it doing the extra shot, they took it back and replaced a couple of parts, although they said they were unable to replicate the problem.
If anyone can offer any help with this, or suggestions for anything I might be doing wrongly, I would be grateful.