SHIFT + TAB stopped working for unindenting things

I am not sure what the cause of this is, but for some reason shift + tab stopped working for me to unindent and essentially do ‘reverse tab’. I don’t really know the reason why and I would appreciate it a lot if someone may help me fix this issue. It’s very strange.

So for example before, pressing SHIFT + TAB here in KM :

Would do this :

And this worked universally for all applications.

This issue is not KM related per say but is more macOS related, is there anything in macOS that might have flipped the switch so to speak and made this behaviour go away?

Apparently that is not the default behaviour on macOS when as I thought it was, perhaps that is not possible to do, for some odd reason I remember it working though.