after some updates i also noticed that merkuro was installed.
so, merkuro did not start.
i tried it from the terminal.
merkuro-calendar
file:///usr/lib/qt/qml/org/kde/kirigami.2/private/globaltoolbar/ToolBarPageHeader.qml:32:9: QML Loader (parent or ancestor of QQuickLayoutAttached): Binding loop detected for property "maximumWidth"
zsh: segmentation fault (core dumped) merkuro-calendar
If anyone also have this problem, I have a solution here:
https://bugs.kde.org/show_bug.cgi?id=472793
LANG=en_US.UTF-8 LANGUAGE=en_US merkuro-calendar => work
I’ve set a post on disuss. since all KDE developers are represented there this issue will be fixed hopefully