I was hiking yesterday with my Z8 and Z 400 on a sling strap so that the camera was at my hip. I stopped for a breather and grabbed the camera and noticed the door was open, furthermore the card was partially ejected and no doubt would have fallen out in short order. Although I tend to have the bottom of the camera against my hip, it must have rotated at some point so that the door was bumped and then the card must have been bumped in order to eject it.
I'm a little disappointed that Nikon decided to go back to the same door style as the Z7 and did not use the same door as the Z9. I've never had the door open on the z9 in the 17 months that I've been using it. I know that some people complained that the z9 door was too cumbersome to open. Perhaps the complaining was a little too loud and now we've taken a step back to a door that opens a little too easy.
Still love the Z8, but now a strip of gaffer tape adorns it to add some more security.