Comment 4 for bug 2018037

The process seems to run out of a systemctl user session.

If you click on Updates in the System Tray and find the process running plasma-discover you can track it down using systemctl --user status.

This is what I see once I click on Settings:

[gmllaptop]: systemctl --user status app-org.kde.discover-b6ad4ccf939247e2b7d6ab273552ae02.scope
● app-org.kde.discover-b6ad4ccf939247e2b7d6ab273552ae02.scope - Discover - Software Centre
     Loaded: loaded (/usr/share/applications/org.kde.discover.desktop; transient)
  Transient: yes
     Active: active (running) since Sat 2023-04-29 00:28:19 BST; 2min 15s ago
      Tasks: 27 (limit: 18639)
     Memory: 278.5M
        CPU: 2.777s
     CGroup: /user.slice/user-4410.slice/user@4410.service/app.slice/app-org.kde.discover-b6ad4ccf939247e2b7d6ab273552ae02.scope
             └─3307 /usr/bin/plasma-discover --mode update

Apr 29 00:28:22 gmllaptop DiscoverNotifier[3307]: took really long to fetch KNSBackend(0x562127ab7870, name = "/usr/share/knsrcfiles/plasma-themes.knsrc")
Apr 29 00:28:22 gmllaptop DiscoverNotifier[3307]: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/private/globaltoolbar/ToolBarPageHeader.qml:80:13: QML Binding: Binding loop detected for property "value"
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/templates/InlineMessage.qml:257:13: QML SelectableLabel: Binding loop detected for property "implicitWidth"
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/templates/InlineMessage.qml:257:13: QML SelectableLabel: Binding loop detected for property "implicitWidth"
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: Could not create delegate for ToolBarLayout
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/ActionToolBar.qml: Object or context destroyed during incubation
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: Could not create delegate for ToolBarLayout
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/ActionToolBar.qml: Object or context destroyed during incubation
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: Could not create delegate for ToolBarLayout
Apr 29 00:30:18 gmllaptop DiscoverNotifier[3307]: kf.kirigami: file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami.2/ActionToolBar.qml: Object or context destroyed during incubation

Also, once this happens and you close the Updates window you cannot open it again from the System Tray until you kill it (the System Tray will report it has crashed).