I went ahead and installed it on my two KDE systems: one uses Intel Iris Xe, and the other uses Nvidia.
The Nvidia computer (proprietary driver) has no issue with Shutter. (Fully updated system.) However, the one using Intel GPU has the same issue as seen in this thread.
This is consistent with the infos we collected so far. So, to further narrow it down, I’d like to try and downgrade the Xorg related stuff. But there are 41 packages on my list…
edit: I think, somewhere within those 42 posts should be the answer to everything, but somehow I cannot find it…