Just to let you know that my lung issue is an interstitial lung disease. My lung capacity now hoovers at about 50% and am immune compromised. Normally I say, "stable is good."

Prayers you will recover with no complications 🙏
It is certain that you had PFTs done and perhaps they told you things about your FEV-1 or other numbers regarding your Vital Capacities or Inspiratory Capacity. I do not post images out here in many years, as I quit using PCs long ago and my Internet Provider (Xfinity) no longer supports image holding and they deleted hundreds of my images. Still, one can search images of PFT values. I always found the blocks rather than the graphs to be easier to read. All of the capacities and volumes are related in unique ways.
Hang in there, interstitial lung disease is often congenital. Perhaps that is so with you. People live good lives even with that malady, which are not just 1 particular thing.
Anyhow, those numbers regarding Lung Capacity were collected something like 50-60 years ago, from then young Military Personnel. Perhaps they have done new studies in recent years but I am not aware of it.
The 50% stuff could be deceptive.
Meanwhile, I would guess that they have prescribed you for BiPAP. BiPAP is a very cool therapy. Some people need a bit of adjustment but that stuff saves lives and provides comfort.