FWIW your attitude is correct in general. When you have a bug with a distro package and you haven't root-caused it yourself to a bug in upstream source, the best thing is to report it on the distro tracker. The distro package maintainer can then do that root-causing, and if they determine it's an upstream bug they can forward it to upstream.
This is how it used to work (and still does with enterprise distros, because you might as well use the support contract you paid for). But users these days have gotten savvy enough to start engaging with upstream directly, especially since many upstreams have made it easier to be engaged with by using GitHub etc instead of mailing lists etc.
Sometimes engaging directly with upstream works, as it apparently does with KDE according to other comments in this thread. Sometimes upstream gets annoyed because they only care about their tree, eg systemd devs get annoyed when users report bugs that have long been fixed in master, but still exist in an old stable release that happens to be the latest on some LTS distro. It depends on the project, so when in doubt start with the distro tracker.
This is how it used to work (and still does with enterprise distros, because you might as well use the support contract you paid for). But users these days have gotten savvy enough to start engaging with upstream directly, especially since many upstreams have made it easier to be engaged with by using GitHub etc instead of mailing lists etc.
Sometimes engaging directly with upstream works, as it apparently does with KDE according to other comments in this thread. Sometimes upstream gets annoyed because they only care about their tree, eg systemd devs get annoyed when users report bugs that have long been fixed in master, but still exist in an old stable release that happens to be the latest on some LTS distro. It depends on the project, so when in doubt start with the distro tracker.