Using this 
csr-active-config dwgAAA== works to disable SIP correctly on Catalina and previous macOS, but on BigSur 
csrutil status with "Custom Configuration" and 
csrutil authenticated-root disabled.
Instead this new value 
fwgAAA== works to disable SIP correctly on BigSur and authenticated-root, but on Catalina and previous macOS SIP is in "Custom Configuration".
Here is the config.plist example :
	
	
	
		Code:
	
	
		    <key>NVRAM</key>
    <dict>
        <key>Add</key>
        <dict>
            <key>4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14</key>
            <dict>
                <key>UIScale</key>
                <data>AQ==</data>
                <key>DefaultBackgroundColor</key>
                <data></data>
            </dict>
            <key>7C436110-AB2A-4BBB-A880-FE41995C9F82</key>
            <dict>
                <key>boot-args</key>
                <string>-no_compat_check</string>
                <key>csr-active-config</key>
                <data>fwgAAA==</data>
                <key>run-efi-updater</key>
                <string>No</string>
            </dict>
        </dict>
        <key>Delete</key>
        <dict>
            <key>4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14</key>
            <array>
                <string>UIScale</string>
                <string>DefaultBackgroundColor</string>
            </array>
            <key>7C436110-AB2A-4BBB-A880-FE41995C9F82</key>
            <array>
                <string>boot-args</string>
                <string>csr-active-config</string>
                <string>run-efi-updater</string>
            </array>
        </dict>