Well lightning network is considered decentralized finance https://www.defipulse.com/projects/lightning-network

It works when nodes have many channels and have liquidity to help move payments around and get paid for forwarding payments to the next hop.

I'd say its more decentralized than most "defi".

• Different client implementations of it
• Different bitcoin node implementations of it
• Way more nodes are being run than "defi" right now