kex_exchange_identification: client sent invalid protocol identifier

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Jun 16 20:36:37 pve sshd[2516539]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:37 pve sshd[2516539]: banner exchange: Connection from 192.168.1.197 port 45890: invalid format
Jun 16 20:36:37 pve sshd[2516543]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:37 pve sshd[2516543]: banner exchange: Connection from 192.168.1.213 port 54146: invalid format
Jun 16 20:36:38 pve sshd[2516547]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:38 pve sshd[2516547]: banner exchange: Connection from 192.168.1.214 port 51892: invalid format
Jun 16 20:36:38 pve sshd[2516548]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:38 pve sshd[2516548]: banner exchange: Connection from 192.168.1.175 port 47666: invalid format
Jun 16 20:36:39 pve sshd[2516560]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:39 pve sshd[2516560]: banner exchange: Connection from 192.168.1.212 port 41528: invalid format
Jun 16 20:36:40 pve sshd[2516592]: error: kex_exchange_identification: client sent invalid protocol identifier ""
Jun 16 20:36:40 pve sshd[2516592]: banner exchange: Connection from 192.168.1.197 port 60292: invalid format

Any idea what this means? I see this on server side when sshfs clients do connect.