https://reference.opcfoundation.org/v104/Core/docs/Part14/7.2.3/ says:

Timestamp DateTime A timestamp which applies to all values contained in the DataSetMessage.
This value is optional. The presence of the value depends on the setting in the JsonDataSetMessageContentMask.

Status StatusCode A status code which applies to all values contained in the DataSetMessage.
This value is optional. The presence of the value depends on the setting in the JsonDataSetMessageContentMask.

Clarifications needed:
1) "A timestamp which applies to all values contained in the DataSetMessage.". Is it source timestamp, server timestamp, or both?
2) What should the subscriber do if it receives a message that has the Timestamp or StatusCode field present at the DataSetMessage level, and at the same time, the field value is formatted as DataValuie and already the timestamp(s) and/or status code? a) use the info from DataValue (I prefer this solution), b) use the info from DataSetMessage, c) reject the message ?