You can try running it in Python directly instead of using a process manager, also if it is graphical system logging in or out or lock screening may be sending accidental keystrokes. You could try testing it out without running anything else and using a more plain terminal emulator like Kitty or Alacritty.

This is because some programs which monitor or automate keystrokes can send keyboard interrupts. Another recommendation is trying to run it without a graphical interface if that is an option in a plain console without a desktop environment as this is more secure and less likely so be interrupted.