This merge request implements an idea in https://bugs.kde.org/show_bug.cgi?id=443235 for a different style of grouped task indicator:
In this MR, it is implemented to only use this new style when the active Plasma theme lacks the grouped task indicator elements in its tasks.svgz file. So if we want to use this in the Breeze Plasma theme, we would have to remove those graphics.
This merge request is RFC because I am not really married to the idea myself, and I just wanted to try it out to see if I liked it. I don't hate it, and I think it's an intriguing idea. But if nobody else likes it I would be happy to abandon the idea and close the bug report. So consider this to be an idea discussion in the form of a merge request. :)
If you don't feel like modifying your Plasma theme, the easiest way to test is by changing !taskSvg.hasExpanderGraphics to false in applets/taskmanager/package/contents/ui/Task.qml
BUG: 443235 FIXED-IN: 5.24
cc @teams/vdg