By default Jitsi installations auto configure with the Jitsi/8x8 STUN servers, which help them discover their public IP addresses. I encourage you to have a look at the STUN protocol for yourself but the way I’d summarize it is this:
A STUN request, sent by a Jitsi client or bridge, is simply a message that asks the STUN server: please tell us where you received this message from. The STUN server responds statelessly by essentially copying the source IP address into a response and sending it back. We store none of that information past the duration of the transaction, but it does expose said public IP to the server.
If you are uncomfortable with this you can remove the STUN server from the clieint config.js and the JVB sip-communicator.properties file. Keep in mind that the former will effectively disable P2P support for clients and the latter would impact the ability of the bridge to function behind a NAT.