Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

   * What led up to the situation?
Upgrade from Debian 10 to Debian 11 via "apt-get distupgrade"

The Control Key is not working anymore in KDE applications. All Control
related keybindings do not produce a reaction.

/etc/default/keyboard is configured to change keyboard layout with
lwin_toggle. This behaviour does not work anymore in X11.

In the terminal console (outside of X11) key-settings according to
/etc/default/keyboard work correctly.

In X11 inside Firefox and Thunderbird, the Control Key works correctly.

Control Key  does not work in KDE applications: kwalletmanager, kate, konsole,
dolphin,...

* What exactly did you do (or not do) that was effective (or
     ineffective)?
Put default (us, 101-keyboard) settings into /etc/default/keyboard instead of my custom settings. Problem remains.

Output off "xev":
Control Key pressed: keycode 37, Super_L
LWin Key pressed: keycode 133, Control_L
RControl Key pressed: keycode 105, Control_R

Here it seems that there is some confusion between Super_L and
Control_L.

Fiddling with the shortcut-manager in the kde system settings leads me to the
conclusion, that some mapping is not correct, because configuring a new
keyboard shortcut shows Meta+Ctrl when pressing only the Control key.

   * What was the outcome of this action?
None of my own investigations has led to the origin of the problem.
   * What outcome did you expect instead?
...