A long time ago I read an article in a science magazine about children who stutter, and it was noted that those who stutter in speech can often sing smoothly. I thought at the time that the most probable reason for that is that a different part of the brain controls words being sung than words being spoken.

Maybe the same is true for Covid sufferers. Maybe a different part of the nervous system handles breathing for singing versus breathing for ordinary times, and after Covid, that part of the nervous system is in better shape.