( windows key + . ) is putting an ‘e’ char in front of an input section (any). It is showing the password in gdm login page and even making password visible in sudo password taker before giving the input.
This is expected; Windows+. enables the emoji picker. You can either type some emoji description, or type the Unicode point in hex, and press space to replace it or cycle through options. If you type something that isn’t recognizable as an emoji, then nothing happens. You can press Escape to get out of the emoji picker.