The Möbius Sync app doesn’t collect any data about you. There are no ads and no analytics (other than the standard Apple App store analytics). Syncthing itself is also very privacy and security conscious - see https://docs.syncthing.net/users/security.html.
In future we plan to enable the standard Syncthing anonymous usage report on an opt-in basis. This policy will be updated when that happens.
The mobiussync.com website is hosted by Github Pages, who may collect basic user data like IP addresses, but we do not have access to this. We have not added any analytics to the website.
Updated paragraph about website as hosting is moved from Google Sites to Github Pages.