rippled version 2.4.0 added support for canonical ledger entry names ( XRPLF/rippled#5271 ) but the AccountObjects request model hasn't been updated, so it rejects such usage.

example request:

response = client.request(AccountObjects(
            account=wallet.address,
            ledger_hash=ledger_hash,
            type="Escrow",
            marker=marker
        ))

Should be valid but fails with this error:

{'type': "type is <class 'str'>, expected typing.Optional[xrpl.models.requests.account_objects.AccountObjectType]"}