Ok the /etc/resolv.conf is a sym link to missing file
lrwxrwxrwx 1 root root 28 mar 24 20:52 resolv.conf -> /var/run/connman/resolv.conf
Which pointed me to this discussion: Problem with resolv.conf on NFS root install since march update
And the proper solution seems to be:
sudo unlink /etc/resolv.conf
sudo systemctl restart connman
Now resolv.conf is created with a proper value, I do hope that this is not a general bug as it could cause a lot of issues to people as it is very difficult to identify.