Due to changes made to the user agent in iPadOS 13, iPads were identified as macOS devices. This change propagated progressively from September to December,
and required an adjustment to the data in that timeframe. In December, roughly 4.2% (overall) of U.S. macOS share was from iPadOS 13, which is mostly corrected. However, it was not
possible to completely identify and correct the data, so from September to December, macOS share has 1-2% of U.S. share from iPadOS 13.