ssh protocol identification string lack carriage return
ssh-2.0-openssh_8.2p1 ubuntu-4ubuntu0.4 invalid ssh identification string.what is ssh identification string
invalid ssh identification string.
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protocol identification string lack carriage return
telnet invalid ssh identification string

It means that the SSH client didn't actually speak SSH to the server. My best guess would be some sort of transparent proxy or IDS getting identification string from (SCANNER_IP) Mar 3 10:15:18 target sshd[1471]: Protocol major versions differ for (SCANNER_IP): SSH-2.0-OpenSSH_6.6.1 vs.