A wallet used to make a trade on Matcha, where Uniswap was a liquidity source, is not eligible to claim UNI tokens unless it interacted with the Uniswap platform directly before September 1, 2020 (the date of the UNI snapshot).
Matcha uses the 0x API, which aggregates liquidity through our Exchange Proxy smart contract. All Matcha users interact with this single contract. For this reason, even if your trade was routed 100% to Uniswap, your wallet address did not interact directly with their platform.
Note: A proposal was made Uniswap's governance forum to include wallets that interacted with Uniswap only via a proxy contract, and before September 1, in the UNI distribution. On behalf of all of the 0x API integrators, including Matcha, 0x Labs submitted an application to support the proposal. We still encourage our users to participate in the discussion if this is something that they support.