The following now returns the correct dispute game commit:
```rust
let builder = OpEvmEnv::builder()
    .dispute_game_from_rpc(
        optimism_portal,
        Url::parse(l1_rpc_url).expect("Failed to parse RPC URL"),
    )
    .game_index(DisputeGameIndex::Finalized);

let op_env = builder
    .rpc(Url::parse(l2_rpc_url).expect("Failed to parse RPC URL"))
    .build()
    .await
    .expect("Failed to build OP-EVM environment");

let op_env_commitment = op_env.commitment();
```