Today, a issue occured with my MacBook that ssh hanged at rekey after 134217728 blocks, it seems that something wrong with ssh(ssh agent).
After search on the internet, I noticed that the openssh I use is version 8.8p1, and macports has dropped the support for dropped support for launchd in ssh-agent. Then can unset SSH_AUTH_SOCK environment variable to workaround with this issue.
Another solution can use gpg-agent work as ssh-agent,see Make SSH use gpg-agent.