No, your IP address is not revealed when you use Session. Session lets you send messages without revealing your metadata.
In typical messaging apps, metadata is the information created when you send a message—everything about the message besides the actual contents of the message itself. This can include information like your IP address, the IP addresses of your contacts, who your messages are sent to, and the time and date that messages are sent.
It is impossible for Session to track users’ IP addresses because the app uses onion requests to send messages. Because Session doesn’t use central servers to route messages from person to person, we don’t know when you send messages, or who you send them to.