Nostr: Are my Nostr posts anonymous?

Short answer

A public post is signed by a stable public key, so people can link its activity over time. That key may be pseudonymous, but profile details, writing, payment information, and relay connections can reveal identity. Nostr does not automatically hide your network address from the relays you contact. Use separate identities and network protections only after understanding their limits.

Sources

NIP-01: Basic protocol, NIP-65: Relay lists.