Excerpts: "The Find My network uses end-to-end encryption so that Apple cannot see the location of any offline device or reporting device."
"If you and your friend are both on iOS 17, your location will not be accessible to Apple. If you have a preexisting sharing relationship with a friend who is not on iOS 17, your location may be accessible to Apple if it is actively requested by a friend you are sharing with. Your location is retained for up to 24 hours in order to provide the service, after which it is deleted."
"Devices in the Find My network use Bluetooth wireless technology to detect missing devices or compatible items nearby, including AirTags and compatible third-party products registered to your Apple ID, and report their approximate location back to the owner. If a device is turned off or erased, that location is also visible to members of the owner’s Family Sharing group with whom they have chosen to share the location. The interaction is end-to-end encrypted, and Apple cannot see the location of any offline device or reporting device."