Shallow breathing (hyperventilation) also triggers a stress response it raises your cortisol. It brings you into your fight or flight (high cortisol) mode while deep breathing activates your rest and digest mode (low cortisol).
You will breathe more air but will absorb less oxygen in the blood so you see how this is an unhealthy pattern.

It will also ruin your sleep bc the airway isn't stable and will collapse when sleeping. the tongue will be low in the mouth and that damages your facial development. This chronic "air hunger" feeling will make you stressed in situations where you have no reason to and will damage your social life people will sense the stress from your body language and body odor. You will also have anxiety.

Important to know it's only possible to really breathe correctly if your whole body is in balance and stacked well so your diaphragm actually has leverage. It's possible to change unhealthy breathing patterns but it takes a lot of time with exercises.

The chronic stress and bad sleep are obviously gonna damage your health so if you want elite health fix your breathing. I have made good progress and I am so much calmer in social situations or in any situation my baseline cortisol is so much lower. Your voice also gets deeper chest breathing makes your voice sound high pitched and annoying. Nothing is more off putting when talking to someone and they have that angry look on their face when they have no reason to be stressed. So much more pleasing to look at a relaxed face. Stress is contagious and calmness is too. Both with active biological mechanisms btw.