Export network configuration
Referring to https://discussions.apple.com/thread/7305662, same issue macOS Big Sur, same problem on both Mac Mini m1 and MacBook 16".
Even after rebuilding the preferences.plist by deleting it ( sudo rm /Library/Preferences/SystemConfiguration/preferences.plist ) and immediately rebooting, it is not possible to export any network configuration, including a freshly created VPN IPSec connection.
When the "Export Configurations" is greyed out, there is no indication whatsoever on what the problem is, it would improve my user experience a lot if there would be.
IMHO, recovering corrupted network config preferences happens a lot lately, and having only a command line instruction to recover from it is… again a very bad user experience, taking into account that your Mac becomes a bit like just a paperweight, when it is not able to network.
It seems to me that this part of macOS needs a little more attention.