Looker allows you to download and export data in several different formats (for details see the Downloading Looks and Public Sharing, Importing, and Embedding docs pages). As of Looker 3.52, when you download or export data, pivoted columns can be made to look more like they do in Looker.
This new format is associated with the Single Row Table Headers legacy feature (for more details see the Legacy Features docs page). By default, this feature is checked, which means that no change in behavior will occur. If you want the new behavior, un-check this legacy feature and click the Update Legacy Features button.
This new format should make exported data easier to read. However, if you use exported data as an input to other systems, you may need to adjust how those systems parse datasets that use pivots.
Appearance in Looker
When you pivot a dataset in Looker, it appears like this before you download it:
Old Download Behavior
The old behavior places all pivoted column headers on a single row, like this:
New Download Behavior
The new behavior uses multiple rows to deal with pivoted headers, which makes them look more like the data does in Looker. It is also more space efficient: