On the cmd line I can successfully do ...
$ git clone git@raspi4:sudoku
...
Receiving objects: 100% (35/35), 13.19 KiB | 2.64 MiB/s, done.
In sourcetree, I see ...
ssh: connect to host raspi4 port 22: Undefined error: 0
fatal: Could not read from remote repository.
This happens on MacOS after an upgrade to Sequoia.