/usr/libexec/openssh/sshd-keygen in Fedora's openssh-server-7.9p1-5.fc30.x86_64.rpm. It's a script to create the host keys. There's a systemd service that goes with it,
The service checks if a particular host key doesn't exist, and runs the script which just calls
ssh-keygen to create them. So, if the host keys don't exist or get deleted, they're regenerated the next time they're needed.
There's also mentions of
sshd-keygen in the Fedora wiki, in Changes/Remove slogin and sshd-keygen.
It mentions removing "sshd-keygen, a legacy Fedora init script" (and replace it with a proper systemd service) and mentions "Applications/services that needs to make sure that ssh host keys are available".
Yours might be a different implementation, but I suppose it's safe to say that it's for the same purpose.