transparent window with nvidia offload

When trying to use the Wayland backend of qt-webengine to render to a screen via Nividia's PRIME render offload feature (on their proprietary driver), all I get is a transparent window.

I initially reported this issue downstream via qutebrowser:
https://github.com/qutebrowser/qutebrowser/issues/7584

I also posted an error log in this comment:
https://github.com/qutebrowser/qutebrowser/issues/7584#issuecomment-1468475753