I've just installed MacOS Ventura and found that I could no longer log in to the UTM via root SSH. If anyone else has this issue, the following worked for me:
Make a copy of /etc/ssh/ssh_config just in case ;)
sudo cp /etc/ssh/ssh_config /etc/ssh/ssh_config.bak
sudo nano /etc/ssh/ssh_config
Add the following at the end of the file:
Save (If using nano CTRL+X then Y then press return)
Should work fine after that.