The problem when you seemingly configured all right and Google’s DNS resolvers are good:
nameserver 8.8.8.8
nameserver 8.8.4.4
But system still shows wrong information
Install resolvconf if needed
sudo apt-get install resolvconf -y
You need to disable systemd-resolved to get rid of 127.0.0.53 from your /etc/resolv.conf file
sudo systemctl disable systemd-resolved
Then update /etc/resolvconf/resolv.conf.d/base to reflect correct resolvers:
sudo vi /etc/resolvconf/resolv.conf.d/base
nameserver 8.8.8.8
nameserver 8.8.4.4
Than run next command to update /etc/resolv.conf file
sudo resolvconf -u
And recheck your /etc/resolv.conf file
cat /etc/resolv.conf
Should be good now
PS. If this doesn’t work then try to reboot your machine and re-run
sudo resolvconf -u