Note that you can replace almost all of your designer script with anchors.
The purpose of AutoScaleAll is to adjust the layout based on difference between the loaded variant and the actual screen size. The assumption here is that you designed the variant exactly as you want it.
Now when you load it on a larger or smaller device AutoScaleAll slightly increases or decreases the dimensions. If the device exactly matches the variant then it doesn't do anything.
In most cases it is recommended to start with the standard phone size variant and let AutoScale and the anchors resize the layout.