0xdb3e2198?0xdb3e2198 is the function selector for exactOutputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160)). Uniswap V3 swap for an exact output.
When a transaction's data begins with 0xdb3e2198, it is calling exactOutputSingle. The selector is the first four bytes of the keccak-256 hash of the signature exactOutputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160)), which is how wallets and explorers work out which function a payload is for.