Brightness shortcut no longer works in Game Mode!?

Hello, I have a question.
I reinstalled Bazzite on my old Steam Deck LCD a few days ago (GNOME). I noticed that quite a few things have changed in Game Mode. That’s generally fine, but unfortunately the screen brightness no longer works the way it used to.

I can still change the brightness through the menu, but ⋯ (three-dots button) + Up/Down no longer works.
Is this intended behavior? Is there a new shortcut for this? I’ve tried everything, but it just doesn’t work.

Is there any way to reconfigure this somewhere? Using the menu every time is a bit annoying in the long run.