server section applying where it is not expected to

Hi.

I have set up a server section for a mailman list using

server {
listen xx.xx.xx.xx:80;
server_name lists.example.org;
location = / { rewrite ^ /mailman/listinfo permanent; }
location / { rewrite ^ /mailman$uri; }
}
[...]
}

as I found examples on the web, e.g. https://mywushublog.com/2012/05/mailman-with-nginx-on-freebsd/.

Now, using some other subdomain like http://test.example.org/, the URL gets rewritten to /mailman/listinfo too, and so I suspect that this lists.example.org server section also applies to test.example.org -- which I didn't expect. Of course, the IP address is the same for all these domains and sundomains.

Has one of you guys and gals seen such a behaviour before? Does that ring some kind of bell?

Thanks for your time,
w6g