The description says it's private, but the legalese it makes you agree to makes no promise. Rather, the opposite:

> We collect information about your activity in our services

Source: https://policies.google.com/privacy#infocollect

The app is open source[0], although given Apple's stance on sideloading it's hard to confirm if you're using the open version.

[0] https://github.com/google-ai-edge/gallery