higher L1 Sepolia Base estimation than BaseScan Sepolia estimation

[gitkonio]

hey guys

I am trying to calculate Base Sepolia L1 fees via viem op extensions, and currently always getting higher estimation than I can see in basescan.

Here is the example transaction: https://sepolia.basescan.org/tx/0xfa4f7fbd853ec9d06ea8d304c20aece5118c61e44e5870b6f11dcaca27967cfa
Basescan estimates 9184 L1 gas.

However, following code returns estimation of 10284 gas.

public getExtraL1Fees = async (chainId: number, hash: Hex) => {
  const isOpChain = this.isOpChain(chainId);
  const tx = await this.client.getTransaction({
    hash,
  });

  if (isOpChain) {
    const opClient = this.client.extend(publicActionsL2());

    const extraGas = await opClient.estimateL1Gas({
      account: tx.from,
      to: tx.to,
      data: tx.input,
      value: tx.value,
      nonce: tx.nonce,
      gas: tx.gas,
      maxFeePerGas: tx.maxFeePerGas,
      maxPriorityFeePerGas: tx.maxPriorityFeePerGas,
      chain: getChain(chainId),
    });

    console.log('extraGas', extraGas);
    return extraGas;
  }

  return 0n;
};

transaction is triggered by user-operation, so it's ERC-4337 user operation.
do you have an idea why viem estimation is quite higher than basescan estimation?