Ha! I wasn't paying attention and thought that was an iTerm window I'd left open. Running the gui from inside the app Resources folder shows the exact same behavior. 2 process, with one still pegged at 100%. No visible windows.
I'm on OSX 11.2.
No second icon/gui:
but something is happening:
Killing the app causes both processes to go away. I've got a feeling that first one shouldn't be using 99.9% CPU