Yes, I see a problem on iOS.
This behavior applies to the button, and when you use the Image component, everything is displayed well and in focus.
I think so. The button properties are initially set to some initial dimensions, for example, Width = Fit content and Height = Fit contents. With simultaneous use of the blocks BackgroundPicture, Width and Height, the button sizes change, the image is loaded, but it is stretched according to the old button sizes! This is due to the asymynchronous loading of the image and at the time the image is copied, the dimensions do not have time to change.
I set the delay to 1 millisecond and the image is drawn. Two variants of time division of blocks are shown below. Is there a difference in their work? Yes.
When using Var 1 on iOS 10.3, I see that when the button is clicked, the image is displayed in the initially small size of the button, and when the timer is triggered, the defocused image at the modified button sizes first appears, and then the focused one. When using Var 2 the button displays a focused image after a short delay.