I have run the following sudo find / -type f -name "*.network" -not -path "/var/lib/docker/*" to show all the .network files on a fresh 22.04 server install.
Aside from the .network files under /run/systemd/network/ I don't see any other .network files on the system.
Given that /run is tempfs, where is the configuration that I can see in the .network files in /run/systemd/network/ coming from, hard coded defaults in the source code of networkd?