FastInnerShadow scales verticalOffset wrong

An InnerShadow with fast set to true uses an FastInnerShadow. The FastInnerShadow doesn't apply verticalOffset correctly.  It is scaling it based on width instead of height. So the more you have a non 1:1 aspect ratio on your source, the more distortion you will see.

Note: This is not an issue for GaussianInnerShadow.

I've attached a screenshot of the issue and the source code to reproduce it.  The left side uses the GaussianInnerShadow and is correct; all four rectangles have the proper inner shadow.  The right side uses FastInnerShadow and boxes B and C are distorted; B is stretched while C is squished.  But A and D are correct because the Rectangle is a square.

From FastInnerShadow.qml, lines 72-83, in Qt 5.15.2:

72.    ShaderEffect {
73.        id: level0
74.        property variant source: sourceProxy.output
75.        property real horizontalOffset: rootItem.horizontalOffset / rootItem.width
76.        property real verticalOffset: rootItem.verticalOffset / rootItem.width
77.        property color color: rootItem.color
78.
79.        anchors.fill: parent
80.        visible: false
81.        smooth: true
82.        fragmentShader: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/fastinnershadow_level0.frag"
83.    }

On line 76, verticalOffset is being divided by width instead of height.  Changing line 76 to...

property real verticalOffset: rootItem.verticalOffset / rootItem.height

...fixes the issue.