Big Sur 11.3 (20E5186e). I thought they had fixed this by now?.. My guess is this is because of a "rat's maze of virtual pipes" in the bowels of CoreAudio? Is it known for certain that this is a software problem, or the DAC chip?

Scribble and the new APIs to support it in your app. As far as I can tell, these APIs are only available in UIKit and not SwiftUI SwiftUI can bridge with UIKit, so how much does this really matter? (I'm not very familiar with either)