400: a date parameter is not a calendar day or an RFC 3339 instant with an explicit offset, or date was combined with from/to, or from and to mix the two forms, or to was given without from.
e.g. "from must be a calendar day (YYYY-MM-DD) or an RFC 3339 instant with an offset (e.g. 2026-09-13T14:00:00Z)."
400: a date parameter is not a calendar day or an RFC 3339 instant with an explicit offset, or date was combined with from/to, or from and to mix the two forms, or to was given without from.