It is your own device actively checking on you for misbehaving. Completely different from cloud providers checking on renters for misbehaving in their infrastructure.
Your phone will listen to instructions from 3.rd parties to check on you and report you to the police(with Apple as a dispatcher).
Well, no... the cloud provider (Apple in the case of iCloud) will check on you and potentially report you (just like all the other cloud providers do), but without scanning all your files in the cloud (unlike all the other cloud providers).
As I said, your phone doesn't even know if anything matched.
The point is, your phone follows instructions from 3rd parties on scanning your data and reporting back the results. It’s processing your files accordingly, with the intent to to make sure you are not doing anything wrong according to those 3rd parties. Your own device is policing you according to the requirements of those 3rd parties.
