Type "Keyboard_QMLTYPE_22" of base "keyboard" not found when accessing member "style"

For such code

property int fullHeight: inputPanel.height + inputPanel.keyboard.style.selectionListHeight

where inputPanel has InputPanel type (https://doc.qt.io/qt-5/qml-qtquick-virtualkeyboard-inputpanel.html)

I got warning:

Warning: Type "Keyboard_QMLTYPE_22" of base "keyboard" not found when accessing member "style" at

Warning: unqualified access at
    property int fullHeight: inputPanel.height + inputPanel.keyboard.style.selectionListHeight

In VirtualKeyboard/plugins.qmltypes
there are several lines like:

        Property { name: "keyboard"; type: "Keyboard_QMLTYPE_22"; isReadonly: true; isPointer: true }

No description of Keyboard_QMLTYPE_22 type.
But it is normal qml type: https://code.qt.io/cgit/qt/qtvirtualkeyboard.git/tree/src/virtualkeyboard/content/components/Keyboard.qml?h=dev

I tried 5.15.0 and also current master