Apple Photos phones home on iOS 18 and macOS 15
Of course, this user never requested that my on-device experiences be "enriched" by phoning home to Cupertino. This choice was made by Apple, silently, without my consent.
From my own perspective, computing privacy is simple: if something happens entirely on my computer, then it's private, whereas if my computer sends data to the manufacturer of the computer, then it's not private, or at least not entirely private. Thus, the only way to guarantee computing privacy is to not send data off the device.
Turn off Enhanced Visual Search (in the Settings app > Apps > Photos) on every device.