Qt Creator crashes when clicking "Designer" on a QML 2.15 application

EDIT: It also crashes with Kit 6.5.2, so basically always.

To reproduce in Qt Creator 11.0.2 with Kit "Qt 5.15.2 GCC 64bit":

1. Click "Create Project..."
2. Choose "Qt Quick Application (compat)", click "Choose..."
3. Give it a name and click "Next"
4. Leave the rest on default:
   1. qmake
   2. Qt 5.15
   3. <none>
   4. (only) Desktop Qt 5.15.2 GCC 64bit
   5. <None>
5. "main.qml" is shown (code below)
6. Click "Designer" (on the left)
7. Qt Creator window is closed (disappears, crashes)

main.qml:

import QtQuick 2.15
import QtQuick.Window 2.15

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

First I had the same behavior like here: https://forum.qt.io/topic/126576/qt-quick-form-editor-cannot-display-window

PLUS three empty windows opened (as defined by main.qml)

After trying some troubleshooting like enabling/disabling Qt Quick/Insight Plugin, reinstalling Qt Crator and Qt via Maintenance Tool it only crashes every time.