It’s nothing wrong with your keyboard. I have a keychron keyboard with usb-c. It works in dgx spark bios, in its desktop wired or Bluetooth, but not in the recovery mode. So I digged out a decade old classic wired Microsoft keyboard, and it worked. I kept that around because old Raspberry pi 2 had exact same problem. The default keyboard driver the recovery media is loading must be darn old.
That’s exactly the case here. I was using a keychron keyboard as well. Works in bios and desktop but not in recovery mode. Thank you guys for sharing the experience. The problem is now solved