I was unable to login from my old iMac running Yosemite to my new iMac running Ventura using RSA keys. It turns out that RSA key support was disabled in Ventura. To correct the problem, I added the following two lines to the bottom of BOTH /etc/ssh/ssh_config and /etc/ssh/sshd_config on the Ventura side:
SSH login from older hosts running OS X Yosemite 10.10.5 to macOS Ventura 13.2.1 was not working. SSH failed with a “No hostkey alg” error. To correct the problem, I added the following two lines to the bottom of BOTH /etc/ssh/ssh_config and /etc/ssh/sshd_config on the Ventura side: