I wouldn't be surprised if this app collected much less data than the Facebook cancer. Facebook is not only stalking you through its main app but its other brands (Insta, WhatsApp, etc which a lot of people don't even know they're owned by FB) as well as unrelated third-party apps & websites that embed their malicious SDKs.
Facebook is an industrial-scale stalking operation. I doubt FaceApp (or frankly any government actor) could pull off something like that even if they wanted to.
The face picture is not really the problem. The app slurps other data from the device, such as log files, cookies, identifiers, etc. Of course, this app is probably not dissimilar to many of the other 2.5 million Android, 1.8 million Apple, 0.7 million Windows, and 0.5 million Amazon apps. https://www.statista.com/statistics/276623/number-of-apps-av...
It's not better to have your face or other data in a database within reach of your own government. Your government has power over you, other governments do not.
The FBI very specifically is concerned about public/elected officials. You don't think other governments might be interested in data about elected officials?
Facebook is an industrial-scale stalking operation. I doubt FaceApp (or frankly any government actor) could pull off something like that even if they wanted to.