CapsLock not working

Hello

New user of nixos here. Getting slowly to understand some of it. Still a very steep learning curve.

I am currently fighting with a keyboard issue. CapsLock is not working. During the boot process the CapsLock is still working correctly, when the boot generations are shown (in systemd-boot), After that (when the kernel is started?) the capslock stops doing anything.

So far I have found out that apparently the wrong keymap is loaded. At least “dumpkeys” shows indeed for keycode 58 that this is not mapped to CapsLock but instead to CtrlLock.

I have no idea howto change that. I tried many combinations in configuration.nix.

I have these entries in my config files:

   console = {
     useXkbConfig = true; # use xkb.options in tty.
   }
   services.xserver.xkb.layout = "de";

Apart from the CapsLock issue the keyboard is working fine.