In https://github.com/opencollective/opencollective-api/pull/8822, we're going to change the type of the "ExpenseItem.incurredAt" field to match what we're using in various places. After this change, non-ISO dates will be rejected by the API.

Example of incorrect use:

createExpense(items: [{ incurredAt: "2022-01-01" }])

Example of correct use:

createExpense(items: [{ incurredAt: "2022-01-01T00:00:00.000Z" }])

Please note that even though this field accepts a timezone, our frontend will completely ignore the time and treat all dates as absolute values.