In order to maintain support for existing apps in Big Sur built with SDK 10.15 or earlier, Big Sur's version can be considered as 10.16. Likewise, new apps built with the latest version of Xcode will be considered as 11.0. In the context of 4D, this is which is the reason why you may be seeing the command Get system info returning the osVersion property as 10.16 or 11.0 as the result will depend on which macOS SDK is installed on your machine.

Both returned version values are acceptable, just be aware when using this command under Big Sur.