I can login fine with ssh debian@ip and key, but if I try to access su I get prompted for password.
sander@t14-sander:/home$ ssh debian@172.30.35.126
The authenticity of host '172.30.35.126 (172.30.35.126)' can't be established.
ECDSA key fingerprint is SHA256:5iCpj8Ab+tW+QH3fo9C0LeXZmDh7WDYi9OlZbo52q+M.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '172.30.35.126' (ECDSA) to the list of known hosts.
Linux Debian-10-Cloudinit 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1 (2019-09-20) x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Fri Sep 27 10:59:31 2019 from 192.168.5.2
debian@Debian-10-Cloudinit:~$ su
Password:
su: Authentication failure
debian@Debian-10-Cloudinit:~$ .ssh
-bash: .ssh: command not found
debian@Debian-10-Cloudinit:~$ cat .ssh/authorized_keys
||ssh-rsa they is the same as my public key :)||
debian@Debian-10-Cloudinit:~$ su
Password:
su: Authentication failure
debian@Debian-10-Cloudinit:~$