What timestamp is exactly used in "product_data_timestamp" in DataTransfer from Merchant Center

[dtru]

I've enabled the DataTransfer for Merchant Center to see disapproved Products (PRoduct Status) and to create a monitoring dashboard on that.
When I compare the count of SKUs in the Merchant Center Export in Big Query and the List in the Merchant Center interface, there is a difference even if I enable the same filters.
For me it's not clear what "product_data_timestamp" exactly is.. Is it the timestamp when the product was updated or uploaded in Merchant center? or something else? The Time of the run of the DataTransfer is not identical to the procut_data_timestamp so this is not the value of this field.
Can anyone help to explain?
Thanks

[ricconoel]

Based from Merchant Center product schema:

product_data_timestamp -> Timestamp of the product data

So `product_data_timestamp` should reflect the timestamp when the product was modified/created in Merchant Center.

But if you have further questions about the behavior of the data, I suggest to contact Merchant Support.