No problem here (my client is an up-to-date fedora):
ssh -vv root@172.19.12.60
OpenSSH_8.8p1, OpenSSL 3.0.8 7 Feb 2023
debug1: Reading configuration data /home/neo/.ssh/config
debug2: resolve_canonicalize: hostname 172.19.12.60 is address
debug1: Connecting to 172.19.12.60 [172.19.12.60] port 22.
debug1: Connection established.
debug1: identity file /home/neo/.ssh/id_rsa type 0
debug1: identity file /home/neo/.ssh/id_rsa-cert type -1
debug1: identity file /home/neo/.ssh/id_dsa type -1
debug1: identity file /home/neo/.ssh/id_dsa-cert type -1
debug1: identity file /home/neo/.ssh/id_ecdsa type -1
debug1: identity file /home/neo/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/neo/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/neo/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/neo/.ssh/id_ed25519 type -1
debug1: identity file /home/neo/.ssh/id_ed25519-cert type -1
debug1: identity file /home/neo/.ssh/id_ed25519_sk type -1
debug1: identity file /home/neo/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/neo/.ssh/id_xmss type -1
debug1: identity file /home/neo/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.8
debug1: Remote protocol version 2.0, remote software version dropbear_2020.81
debug1: compat_banner: no match: dropbear_2020.81
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 172.19.12.60:22 as 'root'
debug1: load_hostkeys: fopen /home/neo/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
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-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256
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-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@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-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@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-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group14-sha256,kexguess2@matt.ucc.asn.au
debug2: host key algorithms: ecdsa-sha2-nistp521,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes256-ctr
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes256-ctr
debug2: MACs ctos: hmac-sha1,hmac-sha2-256
debug2: MACs stoc: hmac-sha1,hmac-sha2-256
debug2: compression ctos: zlib@openssh.com,none
debug2: compression stoc: zlib@openssh.com,none
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp521
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: kex: curve25519-sha256 need=64 dh_need=64
debug1: kex: curve25519-sha256 need=64 dh_need=64
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ecdsa-sha2-nistp521 SHA256:ME/nPB889AfDGA+lKayagID4y6mXXMC2E3rq2ejiCZQ
debug1: load_hostkeys: fopen /home/neo/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host '172.19.12.60' is known and matches the ECDSA host key.
debug1: Found key in /home/neo/.ssh/known_hosts:135
debug2: set_newkeys: mode 1
debug1: rekey out 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 in after 134217728 blocks
debug1: Will attempt key: /home/neo/.ssh/id_rsa RSA SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx agent
debug1: Will attempt key: /home/neo/.ssh/id_dsa
debug1: Will attempt key: /home/neo/.ssh/id_ecdsa
debug1: Will attempt key: /home/neo/.ssh/id_ecdsa_sk
debug1: Will attempt key: /home/neo/.ssh/id_ed25519
debug1: Will attempt key: /home/neo/.ssh/id_ed25519_sk
debug1: Will attempt key: /home/neo/.ssh/id_xmss
debug2: pubkey_prepare: done
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-256,ssh-rsa,ssh-dss>
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: /home/neo/.ssh/id_rsa RSA SHA256:vDBB91Vnt5v04XwnX9PsZGGWgpbeyTrjbIjLrak1SXc agent
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/neo/.ssh/id_dsa
debug1: Trying private key: /home/neo/.ssh/id_ecdsa
debug1: Trying private key: /home/neo/.ssh/id_ecdsa_sk
debug1: Trying private key: /home/neo/.ssh/id_ed25519
debug1: Trying private key: /home/neo/.ssh/id_ed25519_sk
debug1: Trying private key: /home/neo/.ssh/id_xmss
debug2: we did not send a packet, disable method
debug1: Next authentication method: password
ecdsa-sha2-nistp521 is currently used by dropbear, the must secure that is currently supported.