I think that there should be a setting to change the size of the system tray ions separately from the rest of the panel icons, as they start taking up too much unnecessary space. Reproducible: Always
Similar but not quite the same: https://bugs.kde.org/show_bug.cgi?id=355587
We're already moving away from specifying the panel icon side in this KCM (bug 356712). I don't think we should add more esoteric settings here. Rather, this should be controlled from the System Tray itself. There are two bugs tracking this: Bug 360333 Bug 355587 *** This bug has been marked as a duplicate of bug 360333 ***