Authentication failed when connecting to MacOS host with Xpra

I'm trying to connect xpra from a _Linux client_ to a _MacOS host_. I have xpra and xquartz installed on the MacOS host via homebrew. And I am able to connect to the MacOS host directly with ssh using pubkey authentication. When I try to connect to the MacOS host using xpra I get an Authentication failure. Logs show that it's tried to connect with the correct pub-key:

2025-06-30 17:36:45,926 loaded Ed25519 private key from '/home/cheezsteak/.ssh/id_ed25519'
2025-06-30 17:36:45,943 Authentication (publickey) failed.

Now I'm pretty sure that I haven't set up X11 correctly on the Mac. All I did was install XQuartz. But this looks like an ssh authentication error not an X11 error. **Why is Xpra getting authentication errors when SSH isn't?** I suspect some changes to my sshd_config to enable Xpra support are required. The only changes I've made from the OSX default is PubkeyAuthentication yes and PasswordAuthentication no.