A PayoutItem's amount came back as a string while Payment and Payout amounts are integers, with nothing in the API docs flagging the difference. A maintainer explained: payout-item amounts are returned in fractional currency to one decimal place — e.g. GBP 12.345 is serialized as "1234.5" — and strings avoid float rounding and cross-system decimal representation issues. They agreed to make this clearer in the docs.