Error activating XKB configuration

Hi all,

I’m aware of the topic here. However, in my case, I have not added a new keyboard layout and the message does not pop up at login but whenever I connect my Bluetooth headphones.
Here’s the output of the commands:

$ xprop -root | grep XKB
_XKB_RULES_NAMES_BACKUP(STRING) = "evdev", "", "de", "", ""
_XKB_RULES_NAMES(STRING) = "evdev", "pc105", "de", "", "terminate:ctrl_alt_bksp"
$ gsettings get org.gnome.libgnomekbd.keyboard model
''
$ gsettings get org.gnome.libgnomekbd.keyboard layouts
@as []
$ gsettings get org.gnome.libgnomekbd.keyboard options
@as []

My general keyboard has a German (de) layout though.

Any input would be very welcome.