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clients by default leak users’ IP addresses to relays 

"Your IP address is exposed to the relays you connect to, so consider using a VPN or similar. Some clients also support connecting via Tor. Tor nostr relays exist, but not all clients support Tor nostr relays.

Relays also know which public keys you are requesting, meaning your public key will be tied to your IP address."
https://nostr-resources.com/