Configuring a ProxyVM VPN Gateway

I’ve been asking myself a question for a while. Since the change from iptables to nftables,
I use the network manager rather than the “manual way” as described here and in the official documentation (I use it because I find it more convenient to change vpn servers via the network manager).
I’d like to know if using the network manager can cause more security problems than the “manual way” (knowing that I limit connections only to the IPs of the vpn as @solene does in her tutorial, whether with wireguard or openvpn).