eth_chainId failed while adding the Flashbots RPC to MetaMask

https://docs.flashbots.net/flashbots-auction/advanced/rpc-endpoint

I was adding the RPC endpoint to MetaMask, and it failed because of eth_chainId.

I don’t need a fix or advice on how to work around it, I’m just reporting this for the sake of other users.

<img width="372" height="68" alt="Image" src="https://github.com/user-attachments/assets/c8dba35f-f97b-46ba-8876-7c1d2488a6c7" />