On Solend, 80% of fees are collected as a protocol fee with 20% earmarked as a host fee.
The host fee goes to: (in order of priority)
Users with 1,000 SLND self-referring
Referrals from another address
Permissionless pool creators
Alternative UIs built on Solend smart contracts
When calling the borrow function on the Solend smart contracts, a client may pass in an address to receive the 20% host fee. This is applicable to DeFi strategies integrating Solend (discount off fee), or alternative UIs to Solend's (pass in an address to receive some fees).
This is an incentive to encourage developers to build on top of Solend.