[2023] Darktide sometimes doesn't get window focus

Have you switched to a 4k monitor recently?

It depends on your screen set-up what the correct value will be, but to start with you could try changing fullscreen_output in your user_settings.config to 0.

One of our developers say you may need to experiment with window modes.

You may also wish to try disabling your mods, to see if that could be related.