Yes, that matches my observations. I develop photography software and in early versions of iOS 18, sometimes saving a large image to the camera roll would fail

Yes, that matches my observations. I develop photography software and in early versions of iOS 18, sometimes saving a large image to the camera roll would fail because the daemon in charge of carrying out the photo library transactions would get killed due to low memory. This only happened on devices that ran Apple intelligence. Fortunately they seemed to have fixed that bug around 18.1 or 18.2 if I recall.