Sysadmin doesn't look after the repositories on build.opensuse.org - that is handled by the OpenSUSE KDE Team.
Adding two people who are in that team who may be able to assist.

qtfeedback is unmaintained since 2018, so IMO actively introducing that now is not a good idea.

Thank you for the reply!

I agree it would be great to have a maintainer for it. I don't know an alternative project.
Should it be forked as a KDE project?

For a reference, it's not only for the dialer (and the shell runtime).
PlaMo also uses Maliit keyboard project (It's not a part of KDE codebase though) with the same dependency: https://github.com/maliit/keyboard/blob/master/CMakeLists.txt#L36

Or should I consider contributing with making qt-feedback dependency optional (or dropped) both from Maliit and the Dialer? It probably would require introducing an alternative implementation and upstreaming approve.

Thanks again for the hints!

Hmm, I probably could introduce HAVE_QT5_FEEDBACK approach similar to Maliit to skip CI build issues.

IMO all of those are valid options, no idea what's the best one. If there's someone willing to maintain it, it might even be possible to contribute to qtfeedback upstream and revive it. Only if that's for some reason not accepted by Qt upstream forking it as KDE project should be considered IMO.

Otherwise there appear to be some alternatives like feedbackd from Purism which has a simple DBus API.