/usr/share/gdm/greeter/autostart/caribou-autostart.desktop is in gdm3 3.14.1-7.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | [Desktop Entry]
Type=Application
Name=Caribou
Exec=/usr/lib/gdm3/caribou
AutostartCondition=GSettings org.gnome.desktop.a11y.applications screen-keyboard-enabled
X-GNOME-AutoRestart=true
|