At the end of last year, UNI turned on the protocol fee switch: a portion of transaction fees is collected by the protocol. This is the source of protocol revenue. This portion of protocol revenue isn’t distributed directly as payouts but follows the path of burning UNI: 1. Transaction fees are accumulated in the TokenJar 2. Someone uses UNI to exchange for these accumulated assets 3. The UNI used in the exchange is permanently burned The result is, the more active the trading, the more the protocol collects, and usually, the more UNI gets burned.