It sounds like it's possible that it could've been caused by getting Covid, but not for certain. I've heard of something called "long Covid" where some the symptoms either linger for a long time after the onset of initial symptoms or it leads to other symptoms that linger over the long term.

Yes I believe there are many ways to deal with the issue and improve it over time, and maybe even eliminate it.

Have you been able to exercise or do you normally exercise and how does the breathing issue affect that?