Comment 17 for bug 1876884

After some more research, I found this "Ask Ubuntu" topic, where the exact same problem is reported: https://askubuntu.com/questions/1228433/what-is-creating-run-netplan-eth0-yaml

It seems like "initramfs-tools" is generating the /run/netplan/enp1s0.yaml file, managed by the "system-dnetworkd" renderer. This is why the "NetworkManager" is not able to manage it at runtime, after the system is booted.

As a workaround, you should be able to override this behavior to set "renderer: NetworkManager" in a file sorting lexically after 'enp1s0.yaml' and redirect this network interface to NetworkManager that way.

But generally speaking I think initramfs-tools should cleanup its side-effects after it is done...