I would say same as you visiting a website. If you visit a website they can see your IP, relays can also see it, so either use relays you can trust not to track your IP or use VPN or Tor. Then there is metadata like nostr DMs, some metadata might be visible depending on the client. So generally speaking you can use a VPN or Tor if your IP is a worry, for DMs if privacy is very important you should choose a good nostr chat client or don't use at all.

Relays and web servers can see your IP address when you connect

Use a vpn and your ip won’t be seen by relays