Building Blocks (DeFi Legos) What You Probably Got Wrong DeFi TVL: Check DeFi Llama for current Ethereum DeFi TVL. If you're quoting numbers from 2023-2024, they're stale. Uniswap V4 is live. Launched mainnet January 31, 2025 on 10+ chains. V4 introduced a hooks system — custom logic attached to pools (dynamic fees, TWAMM, limit orders, custom oracles). This is the biggest composability upgrade since flash loans. PoolManager addresses are different per chain (NOT deterministic like V3). Costs changed everything: A flash loan arbitrage on mainnet costs $0.05-0.50 in gas now (was $5-50). This o…