here is the output:
root@proxmox-01:~# ssh -vv proxmox-02
OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r  26 Feb 2019
debug1: Reading configuration data /root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "proxmox-02" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to proxmox-02 [192.168.0.2] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
key_load_public: invalid format
debug1: identity file /root/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u6
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4p1 Debia                                                                                                                                                             n-10+deb9u6
debug1: match: OpenSSH_7.4p1 Debian-10+deb9u6 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to proxmox-02:22 as 'root'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2                                                                                                                                                             -nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sh                                                                                                                                                             a256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-                                                                                                                                                             group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ex                                                                                                                                                             t-info-c
debug2: host key algorithms: 
ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-                                                                                                                                                             256,ssh-rsa,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v0                                                                                                                                                             
1@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@open                                                                                                                                                             ssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
debug2: ciphers ctos: 
chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256                                                                                                                                                             -ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-                                                                                                                                                             cbc
debug2: ciphers stoc: 
chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256                                                                                                                                                             -ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-                                                                                                                                                             cbc
debug2: MACs ctos: 
umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-25                                                                                                                                                             
6-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-6                                                                                                                                                             
4@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: 
umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-25                                                                                                                                                             
6-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-6                                                                                                                                                             
4@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2                                                                                                                                                             -nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sh                                                                                                                                                             a256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-                                                                                                                                                             group14-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp2                                                                                                                                                             56,ssh-ed25519
debug2: ciphers ctos: 
chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256                                                                                                                                                             -ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: 
chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256                                                                                                                                                             -ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: 
umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-25                                                                                                                                                             
6-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-6                                                                                                                                                             
4@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: 
umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-25                                                                                                                                                             
6-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-6                                                                                                                                                             
4@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: rsa-sha2-512
debug1: kex: server->client cipher: 
chacha20-poly1305@openssh.com MAC: <implicit                                                                                                                                                             > compression: none
debug1: kex: client->server cipher: 
chacha20-poly1305@openssh.com MAC: <implicit                                                                                                                                                             > compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:2dfHNKrqePLq+E4EogKsmtDlRUZYKX5RORUUfNIg                                                                                                                                                             n6I
debug1: Host 'proxmox-02' is known and matches the RSA host key.
debug1: Found key in /etc/ssh/ssh_known_hosts:4
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug2: key: /root/.ssh/id_rsa ((nil))
debug2: key: /root/.ssh/id_dsa ((nil))
debug2: key: /root/.ssh/id_ecdsa ((nil))
debug2: key: /root/.ssh/id_ed25519 ((nil))
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,ssh-dss,ecdsa-s                                                                                                                                                             ha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
Enter passphrase for key '/root/.ssh/id_rsa':
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My /etc/pve/priv/authorized_keys file is blank on the ProxMox 5.4 servers, but there is data in the file on my cluster running 5.3.
I never added anything to that file in the working 5.3 cluster, is this something that should be autopopulated during the clustering process?