reFaced

When taking a photo of a person, the app automatically applies slight alterations to your face that prevent unwanted recognition by algorithms that scrape images from the web. It does so entirely on-device so as to safeguard the user's face data. No data leaves the device. The premium version can protect fingerprints as well.
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/