SwiftUI Button is not blurred when disabled in iOS 14.

In the app using SwiftUI, I disabled a button using ".disabled()". In iOS 14, when I tap the button, it seems disabled but the button is not blurred.

It works fine in iOS 15 and 16.

Is this iOS 14 or SwiftUI bug?

If not a bug, I would like to know how to make the button blurred in iOS 14.