By default there is no communication with nostr relays about your tip. It's the same as sending someone a normal Monero transaction outside of Nostr just a little more convenient.

There is an option to make your tip "anonymous" (The general public sees your tip but doesn't know who it is from. Relays know it's from your npub though.)

And a second option to make your tip completely public if you want (everyone sees your tip and knows it's from you).