Comment 6 for bug 1981103

If you changed away from /etc/network/interfaces file to netplan.io configuration (/etc/netplan/...) then you won't need ifupdown. There is a configuartion tool, with simple configs it works: See this info how to convert your network config. But be sure to have physical access to the machine's console: https://gist.github.com/mss/7a8e048dd51e5ef928039f1450ba8f31

I did this for my systems and removed and purged ifupdown. For some configs it may be very complex, especially if you have many tunnels, bridges or other special stuff in /etc/network/interfaces. But for simple single ethernet/wifi device it is easy to migrate using the above GIST.