Terminal:
No device found
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/ToolBarPageHeader.qml:44:9: QML ActionToolBar: Binding loop detected for property "actions"
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/ToolBarPageHeader.qml:44:9: QML ActionToolBar: Binding loop detected for property "actions"
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/ToolBarPageHeader.qml:44:9: QML ActionToolBar: Binding loop detected for property "actions"
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/PageRowGlobalToolBarUI.qml:113: TypeError: Cannot read property 'globalToolBarStyle' of null
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/PageRowGlobalToolBarUI.qml:58:17: Unable to assign [undefined] to QQmlListProperty<QObject>
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/PageRowGlobalToolBarUI.qml:49:13: Unable to assign [undefined] to bool
error debugMessage: No file name specified for reading.
error on: "filesrc location=\"\" ! decodebin ! imagefreeze ! videoconvert ! identity name=last" "gstfilesrc.c(524): gst_file_src_start (): /GstPipeline:pipeline0/GstFileSrc:filesrc0"
error debugMessage: No file name specified for reading.
error on: "filesrc location=\"\" ! decodebin ! imagefreeze ! videoconvert ! bulge name=last" "gstfilesrc.c(524): gst_file_src_start (): /GstPipeline:pipeline1/GstFileSrc:filesrc1"
Stop
QFileSystemWatcher::removePaths: list is empty
QFileSystemWatcher::removePaths: list is empty

OS: Kubuntu 20.04
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.4.0-33-generic
OS Type: 64-bit

works fine for me here on an old Lenovo Yoga 510, maybe something is wrong with the camera? You would have to be a tad more detailed about your hardware

Cheese, VLC and Firefox work though so I think the problem is with kamoso not my camera

File a bug, then: https://bugs.kde.org I still suggest you should be a tad more detailed in a report so this can be reproduced...