Interesting thing about the masks and breathing troubles

You can breath perfectly fine, your brain just thinks it can't.

Your brain: Hey, the mouth and nose are covered. This can only mean we're being deprived of oxygen. I'll tell the lungs to breath harder in order to compensate.

Also your brain: Hey, I'm breathing a lot despite having plenty of oxygen. This must mean I'm struggling to breath.

PS: Obviously, if you're asthmatic or have existing respiratory issues it's different.