None in particular since you still have to connect to a traditional HTTP or WebSocket (although WebRTC is coming soon) servers. So if you connect to a malicious peer they can get your IP can get leaked. But the messaging algorithm is very ad-hoc mesh-networky and UDP-ish. At its core, messages only contain a message ID and a body, these are then daisy chained throughout the servers and clients (they're all peers). Meaning that just because a peer sent you something does not mean they are the originator. However, nothing stops peers from broadcasting their session ID or IP or X-Forwarded-For header. But the counter is also true, the messaging system still works even without that information - which if there are enough peers preserves anonymity. I of course should say the usual disclaimers that small peer groups can be attacked, and larger networks if you have enough intelligently placed peers you can probably calculate triangulation and stuff like that. When you get down to the actual "physics" of stuff, there are lots of tricks/hacks to break any network based on timing and patterns alone.
