LinuxQuestions.org - StrictHostKeyChecking not working

I am trying to ssh to a host via a bastion. I have set StrictHostKeyChecking=no for both ssh as well as the ProxyCommand

Code:

ssh -i ~/mykey.pem-prod hadoop@final.destination.ec2.internal -o "UserKnownHostsFile=/dev/null" -o StrictHostKeyChecking=no -o ProxyCommand="ssh -o StrictHostKeyChecking=no -W %h:%p -i ~/mykey.pem-prod ec2-user@mybastion.us-east-1.amazonaws.com

Sometimes it works but sometimes I get this message:

Code:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

    @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!    @

    @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

    IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

    Someone could be eavesdropping on you right now (man-in-the-middle attack)!

    It is also possible that a host key has just been changed.

    The fingerprint for the ECDSA key sent by the remote host is

    SHA256:

    Please contact your system administrator.

    Add correct host key in /Users/myname/.ssh/known_hosts to get rid of this message.

    Offending ECDSA key in /Users/myname/.ssh/known_hosts:7

    Password authentication is disabled to avoid man-in-the-middle attacks.

    Keyboard-interactive authentication is disabled to avoid man-in-the-middle attacks.

    Error: forwarding disabled due to host key check failure

    ssh_exchange_identification: Connection closed by remote host

I was thinking that StrictHostKeyChecking=no should prevent this problem.