This is what I found about "gossip model" after consulting ChatGPT 3.5. Any expert, please correct or add extra info/context as I'm also interested in learning more about it:

"The gossip model is a communication model used in decentralized systems, such as decentralized relays. In this model, nodes in the network communicate with each other by gossiping or spreading information in a peer-to-peer manner. When a node receives new information, it shares it with a few randomly selected neighboring nodes, which in turn share it with their neighbors, and so on. This process continues until the information has spread throughout the network.

In the context of centralized vs decentralized relays, the gossip model is often used in decentralized relays to disseminate information across the network without relying on a central authority or server. Each node in the decentralized relay network acts as a peer, contributing to the dissemination of information by gossiping with other nodes. This approach provides resilience to failures and censorship, as there is no single point of control or failure in the network."