In order to avoid spam in your feed, you pay a small fee with Monero to a relay. Your pubkey gets whitelisted in that relay, and then you are able to publish events there. Reading from these relays is always free for everyone. This allows getting much more curated and clean results in the global page.
Interested in running your own paid Monero Nostr relay? Take a look a Monero Nostr Paid Relay.