The keys.gnupg.net keyserver is obsolete and yields an error "gpg: keyserver receive failed: No name" (tested under Debian/unstable with 2.2.27). This is confirmed here: https://stackoverflow.com/questions/66217436/gpg-keyserver-receive-failed-no-name
With grep -r keys.gnupg.net, I can see that GnuPG 2.2.29 (i.e. the latest version) still uses it and documents it. This should be updated.