"The key you just pressed is not recognized by SDL"

The key you just pressed is not recognized by SDL. 
To help get this fixed, please report this to the SDL forums/mailing list <https://discourse.libsdl.org/>

X11 KeyCode 151 (143), 
X11 KeySym 0x1008FF2B (XF86WakeUp).

Unfortunately, I’m not really sure what physical key I pressed on my notebook when I got this message.

You most probably pressed the Fn key, see I got an error when pressing my Fn key - #3 by Pacstah and I got an error when pressing my Fn key · Issue #6388 · libsdl-org/SDL · GitHub

I think that in SDL 2.26.0 and newer that message shouldn’t be shown for XF86WakeUp anymore.