Just in case some runs into it again..
I’ve had the same problem with snap installed Docker on Ubuntu 20.04. Syslog was full of docker0 interface errors.
Jan 30 14:28:17 mel kernel: [169365.081105] veth23ac856: renamed from eth0
Jan 30 14:28:17 mel networkd-dispatcher[782]: WARNING:Unknown index 103 seen, reloading interface list
Jan 30 14:28:17 mel systemd-udevd[103811]: ethtool: autonegotiation is unset or enabled, the speed and duplex are not writable.
Jan 30 14:28:17 mel systemd-networkd[730]: veth7651758: Link DOWN
Jan 30 14:28:17 mel kernel: [169365.208636] docker0: port 1(veth7651758) entered disabled state
Jan 30 14:28:17 mel kernel: [169365.212027] device veth7651758 left promiscuous mode
Jan 30 14:28:17 mel kernel: [169365.212031] docker0: port 1(veth7651758) entered disabled state
Jan 30 14:28:17 mel systemd-udevd[103811]: veth23ac856: Failed to get link config: No such device
Latest package straight from docker.com repository solved the problem..