Problem switching from networkd to NetworkManager on Ubuntu 22.04

On an Ubuntu 22.04 instance on Google Cloud, switching from networkd to NetworkManager is easy:

$ sudo apt install network-manager

$ sudo nano /etc/netplan/50-cloud-init.yaml
# add:
network: 
  renderer: NetworkManager

$ sudo reboot

$ nmcli device
DEVICE  TYPE      STATE                   CONNECTION
ens4    ethernet  connected               netplan-ens4

But identical steps on Oracle Cloud results in:

$ nmcli device
DEVICE  TYPE      STATE                   CONNECTION
enp0s6  ethernet  connected (externally)  enp0s6

Why on Google Cloud is the state "connected" but on Oracle Cloud the state is "connected (externally)"?