V2: From 28 Dec 2025, 17% (0% before) fees on Ethereum shared to buy back and burn UNI, From 8 Mar 2026, 17% (0% before) fees on Optimism, Arbitrum, Base, Zora, XLayer chains shared to buy back and burn UNI. V3: From 28 Dec 2025, a portion of fees a collected to buy back and burn UNI on Ethereum, From 8 Mar 2026, a portion of fees a collected to buy back and burn UNI on Optimism, Arbitrum, Base, Celo, WC, Zora, XLayer. V4: No revenue for UNI holders