it doesn’t run a job it waits for your jobs to end. You can set the default want time. Its the same thing on windows that asks programs to close before shutting down. If a critical application got stuck systemd has nothing to do with it

What do you expect from an init system? It’s like saying my cpu is infectious because my computer depends on it

Even Gnome natively supports Wireguard VPN client by default. There is also wireguard tools on apt. wg-quick up /path/to/conf