https://github.com/jackaudio/new-session-manager was originally named https://github.com/linuxaudio/new-session-manager and has since been renamed (you can tell because of the redirect).
The github.com/linuxaudio URL is the one they were using as recently as January this year: https://lists.linuxaudio.org/archives/linux-audio-user/2021-...
When I wrote the parent comment, I did not notice that I was being redirected from github.com/linuxaudio to github.com/jackaudio; I apologize for that mistake.