Umm, isn’t this, like maybe, a good thing? If I want my very expensive iPhone found, I want it found whether it is on or off. If people are worried about being tracked maybe they should carry around a device that is always broadcasting radio signals to third party towers.
Maybe you don't want to be tracked sometimes, and you expect turning off your device to turn it off.
When you turn your phone off there is a message that states:
iPhone Findable After Power Off >
Tapping that shows an alert with a description: iPhone Remains Findable After Power Off
Find my helps you locate this iPhone when it is lost or stolen, even after power off
The location is visible in Find My on your other devices and to people in Family Sharing you share location with.
You can temporarily turn off Find My network and it will resume when this iPhone is turned on again
[OK] [Temporarily Turn Off Finding]
Seems very clear about setting expectations about exactly what your phone will be doing when you turn it "off".