/etc/default/keyboard not loaded at startup

[gwinship <gwinship@protonmail.com>]

I added following configuration to my /etc/default/keyboard

XKBMODEL="pc105"
XKBLAYOUT="gb,de"
XKBVARIANT=""
XKBOPTIONS="grp:win_space_toggle"

BACKSPACE="guess"
however. This does not load at boot.

My configuration

Debian 10.3
i3, xdm
ThinkPad E580

The /var/log/Xorg.log is

[   268.754] (**) Power Button: Applying InputClass "libinput keyboard catchall"

[   268.754] (**) Power Button: Applying InputClass "system-default"

[   268.754] (II) LoadModule: "libinput"

[   268.755] (II) Loading /usr/lib/xorg/modules/input/libinput_drv.so

[   268.763] (II) Module libinput: vendor="X.Org Foundation"

[   268.763]    compiled for 1.20.4, module version = 0.28.2

[   268.763]    Module class: X.Org XInput Driver

[   268.763]    ABI class: X.Org XInput driver, version 24.1

[   268.763] (II) Using input driver 'libinput' for 'Power Button'

[   268.763] (**) Power Button: always reports core events

[   268.763] (**) Option "Device" "/dev/input/event3"

[   268.763] (**) Option "_source" "server/udev"

[   268.766] (II) event3  - Power Button: is tagged by udev as: Keyboard

[   268.766] (II) event3  - Power Button: device is a keyboard

[   268.767] (II) event3  - Power Button: device removed

[   268.781] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input5/event3"

[   268.781] (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD, id 6)

[   268.781] (**) Option "xkb_model" "pc105"

[   268.781] (**) Option "xkb_layout" "gb,de"

[   268.781] (WW) Option "xkb_variant" requires a string value

[   268.781] (**) Option "xkb_options" "grp:win_shift_toggle"

[   268.832] (II) event3  - Power Button: is tagged by udev as: Keyboard

[   268.832] (II) event3  - Power Button: device is a keyboard

I also tried adding the setting using localectl, but this didn't yield any results either.

Best,

Felix