Interesting. I had bad experience with NordVPN, they have many servers, which is a plus, but a good deal of them doesnt function properly unreliable connection and you can only find out which have this by testing each pinging google etc and once you found one that works well, at some later time it stops working well, and then you have to find a new one… ugh, never going back to that shit). Expensive and low max device limit, clunky huge interface and no command line interface. NordVPN is so not recommended for me at least.
Try disabling the Advanced Killswitch and disabling connect on launch, then disconnecting, possibly restarting the app. Then enable both advanced killswitch and connect on launch. Then reconnect. This seems to have fixed the issue permanently for now.