Yeah as Alfie wrote any changes NordVPN make to Wireguard need to be made public. You can ask them for a link to the source code changes they made.
Also, im not so sure its a privacy issue. Wireguard requires fixed IP addresses set for each client in the config file, IP’s internally used to identify each connected client INTERNALLY. This is not public in any way. OpenVPN also requires IP’s, but they are not statically set in the config files, they are dynamically issued on each connection, that is the main difference here. So i guess they are worried that if the Feds raid their server farm, all the config files will show all the connections to users, but that is just a poor implementation server side. If you raid an OpenVPN server farm, all the connections are still in memory until the server is shut down, they would be able to link connections in that way too. Having a server kill switch where it shuts down all processes (for OpenVPN) and an extra wipe of all configs (for Wireguard) would be better for them.
BTW you can check threads about NordVPN. They had a massive privacy leak and did not disclose about it until the hack was made public on Twitter, don’t trust them for anything.