export private key error

[mars-peng-lb]

I’m using @web3auth/modal/react, and the project has already enabled "Enable Key Export", but when calling const privateKey = await provider?.request({ method: "eth_private_key", });, I get an error The method eth_private_key does not exist/is not available.
I want users to be able to export their own private keys. Is there anything else I need to do?
I just ran the official example, added the export function and changed the clientId.