Ethers.js gives "resolver or addr is not configured for ENS name"

Question

I have the following code:

const ethereumProvider = ethers.getDefaultProvider(ETHEREUM_RPC);

const contract = new ethers.Contract(
  CONTRACT_ADDRESS,
  abi,
  ethereumProvider,
);

The package ethers gives me the following error:

Error: resolver or addr is not configured for ENS name (argument="name", value="734574864865375122901309634679882622222228500042", code=INVALID_ARGUMENT, version=contracts/5.5.0)

I don't know where this number comes from. I never give this as an argument anywhere.

Also, this error only occurs when deployed on AWS Beanstalk.