Citizen X is developed with a local first storage principle, a peer to peer data sharing method and a completely decentralized architecture. You are responsible for what you share about yourself, it's your data, with what you write on the pages you annotate, it's your opinions and with the knowledge that you are creating public data available for anyone to see.
Side note: don't annotate anything you don't intend to share with the world. If you don't deactivate the camera when saving the annotation you take a snapshot of the visible page. Now it will stay in your own browser until you share it with someone else but that's still not very safe if it's your bank account, your sexting or your workplace online document.