On your local machine under the account kevin in the file known_hosts there is already an entry for a machine with the IP 192.168.178.73. The file ( known_hosts ) stores a checksum called host key.
Due to the fact that the remote host ( openhab server at 192.168.178.73 ) was recreated or the sshd service was asked to recreate a host key the openhab server now has a new checksum / host key.
This is what the message complains about. To be on the safe side the communication is aborted at this point.
You can edit the local known_hosts file and delete the row for the openhab server.
Then again try to ssh into the server. The message should be gone
