Hello, thanks for the post and the discussion around this. Sorry for the confusion.
Apple reports Big Sur in two different ways depending on if the binary checking the OS build was built on previous versions of Xcode or the newly released version of Xcode 12.
Starting with Jamf Pro 10.25.2, released today, the Jamf Pro management framework has been updated with Xcode 12 so it will now report Big Sur as macOS 11.
Please let us know if you have any questions.