こちらで解決しました。ありがとうございます。
【SSH】REMOTE HOST IDENTIFICATION HAS CHANGED が出た場合の対処法【github】
解決策
% ssh-keygen -R github.com
% ssh -T git@github.com
プロンプトで Yesログ
% git push
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ 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 RSA key sent by the remote host is
SHA256:xxxxx
Please contact your system administrator.
Add correct host key in /Users/xxxxx/.ssh/known_hosts to get rid of this message.
Offending RSA key in /Users/xxxxx/.ssh/known_hosts:1
Host key for github.com has changed and you have requested strict checking.
Host key verification failed.
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
% ssh-keygen -R github.com
# Host github.com found: line 1
/Users/xxxxx/.ssh/known_hosts updated.
Original contents retained as /Users/xxxxx/.ssh/known_hosts.old
% ssh -T git@github.com
The authenticity of host 'github.com (20.27.177.113)' can't be established.
ED25519 key fingerprint is SHA256:xxxxx
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added 'github.com' (ED25519) to the list of known hosts.
Hi xxxxx! You've successfully authenticated, but GitHub does not provide shell access.
% git push
Enumerating objects: 1077, done.
Counting objects: 100% (1037/1037), done.
... (以下、略)