Apple appears to be developing new keyboard shortcuts that will allow users who have a Magic Keyboard or other external keyboard to adjust the brightness of the keyboard keys with shortcuts.
9to5Mac found signs of Apple's work on shortcuts in iPadOS 13.5.5 code. It reports that the code mentions some keyboard shortcuts for alternative function keys.
There is also some evidence found in the code that there are new keyboard shortcuts that can change the brightness of the iPad screen and even the backlight brightness of the keyboard.
It is unclear whether these shortcuts can be customized.
One of the drawbacks of the wonderful keyboard designed for the iPad Pro is that there is no way to quickly change the brightness of the keyboard keys, as the keyboard is missing function lines in order to reduce the size, and if the news is true, then the new improvements will be a great convenience for users.