Regression: Trivial application using QWebEngine crashes in Qt6 but not Qt5

A trivial application that only creates a WebEngineView crashes instantly when compiled with Qt6 (tested: 6.2.4) but works fine with Qt5 (tested: 5.15.9). Attached application output reports warnings and errors.

To facilitate resolving this problem, I created a repository at https://github.com/wagenadl/qwebengine-test-qt6.

To reproduce the problem, simply clone the repo, enter the directory, and:

    mkdir build

    cd build

    cmake ..cmake --build .

    ./qwe

Naturally, I'd be happy to help dissecting this problem with some guidance. It is a show stopper for migrating my NotedELN package (https://github.com/wagenadl/notedeln, https://packages.debian.org/sid/notedeln) to Qt6.