Your question has been answered you just can’t grasp it. You posted talks about oxygen consumption in a conversation about oxygen inhalation, an embarrassing gaffe.
Running with the mouth semi-open is not the same as running with an altitude mask on which is not the same as running while holding your breath, but again you are conflating different scenarios with poor analogies. Hopefully you at least understand that and also understand that they would each have different affects on performance. You don’t have to have your mouth fully agape to intake enough oxygen to surpass what you will be able to deliver to your muscles. This is the crucial piece you can’t understand.
Please try to educate yourself, and better luck next time.