Why does hypoventilation not increase A-a gradient?

I found this on another thread, but it didn't explain it well. So I started a new thread.

If V/Q is less than 1, then A-a gradient will increase.
e.g. pulmonary edema: fluid in alveoli prevents capillary blood from being 100% saturated, then that blood mixes with saturated blood from non-fluid filled alveoli, lowering PaO2.

But if I breathe really slowly, doesn't this also decrease PaO2?
Blood is being perfused at a normal rate, but ventilation has decreased, right? And since PAO2 is...

Why does hypoventilation not increase A-a gradient?

Why does hypoventilation not increase A-a gradient?