REG: TextEdit height gets stuck due to binding loops (forever) or anchor changes (temporarily until further resize event)

TextEdit fails to update its height under certain conditions on Qt 6. This is a regression from Qt 5.15. Screenshots show 3 windows of the same QML scene run with Qt 5.15.10+kde+r158-1, Qt 6.5.2-1, and custom-built Qt dev (from about a week or two ago).

First of all, using anchors + height results in a binding loop. This binding loop is demonstrated in the top-most red block on my screenshots. Note that it still manages to end up with correct size on Qt 5, despite the complains; but fails to do so on Qt 6 after exactly two resizes (expand to single-line and shrink back to multi-line).

Then, an alternative approach using Item::state somehow manages to avoid binding loops between AnchorChanges and PropertyChanges on height. And here I hit a bug in TextEdit resizing/layout: with wrapMode: Text.WordWrap, verticalAlignment: Text.AlignVCenter and a very specific combination of state changes, while shrinking the TextEdit into becoming multi-line, on the very same frame when it becomes multi-line — its height resets correctly but the actual text gets stuck vertically centered; and only on the next resize event (when shrinking further) the text get repositioned correctly on the top.

This works on the first redraw:

states: [
    State {
        name: "multi-line"
        when: target3.lineCount > 1
        AnchorChanges {
            target: target3
            anchors.bottom: undefined
        }
        PropertyChanges {
            target: target3
            height: target3.implicitHeight
        }
    },
    State {
        name: "single-line"
        when: true
        AnchorChanges {
            target: target3
            anchors.bottom: target3.parent.bottom
        }
    }
]

But if you swap height: target3.implicitHeight with height: undefined or remove it altogether, then it gets stuck. If you skip anchors.bottom: undefined, then it break in another creative way: the whole TextEdit becomes thin as it is were single-line while displaying multi-line text layout, and no amount of resizing helps until it is expanded enough to become truly single-line again.

Note: the middle orange block can be "fixed" for Qt 5 by adding the following change set for "single-line" state. It seems like it should conflict with bottom anchor and should actually cause a binding loop, but it… magically doesn't.

PropertyChanges {
    target: target2
    height: target2.implicitHeight
}

I have a theory why height: undefined does not work. "Unset" is the default state for width/height properties, so assigning "undefined" to reset it simply short-circuits and doesn't really do any work, even when doing would help it "unstuck".

I have no idea why explicit anchors.bottom: undefined is required though. "Unset" is also the default state for anchors, so leaving a State which had AnchorChanges in it should restore back the "unset" value, I guess?

And neither of that explain why text layout gets stuck vertically centered, and only fixes up itself on a next polish.