I've moved my default plasmashell panel to the right side of my monitor, so it becomes a vertical instead of a horizontal bar.
Before 5.13 the application launcher icon was horizontally centered in that panel, but only used a "regular" icon size. I haven't measured it, but it's roughly as high as a single entry in the task manager below it.
Since 5.13 the icon fills the entire width of the panel, keeping its aspect ratio while resizing. Having a fairly wide vertical panel, this means the application launcher icon is now occupying more than a third of the panel's entire height.
It would be nice to make the size of the icon either configurable or define "sane" boundaries for the dimensions. (Sane might be hard to argue about here, though)
Fwiw, I definitely preferred the previous behaviour which, while wasting a tiny bit of horizontal space, at least meant I could make the most of the panel.
This is a regression.
It was solved at 2017-06-02. This is the issue: https://bugs.kde.org/show_bug.cgi?id=378443
Git commit 664865f12bc756f4ac75e2915dfebb88aa3abf54 by Eike Hein.
Committed on 24/07/2018 at 08:09.
Pushed by hein into branch 'master'.
Fix Kickoff compact repr size hints in panel
The old code was copy-pasted from Kicker but the wrong code block;
it was the code path for custom button image mode, not the regular
Differential Revision: https://phabricator.kde.org/D14285
M +43 -23 applets/kickoff/package/contents/ui/Kickoff.qml