WebGL lighting not working

Open one of the following sites in a QWebEngineView:

• https://www.airtightinteractive.com/demos/js/ripple-clock/

• https://threejs.org/examples/?q=shadow#webgl_shadowmap

The objects are not lighted, as you can see from the attached screen-shots (web_engine_1.png, web_engine_2.png).

However, the objects are lighted when opening the sites from Chrome on the same machine (chrome_1.png, chrome_2.png).

We assume that the lighting is done per-pixel, in the shader program, in these examples. Other examples which seem to do per-vertex lighting are working correctly (like https://threejs.org/examples/?q=light#canvas_lights_pointlights).

We tried passing various parameters to the chromium engine, including --ignore-gpu-blacklist and  --enable-gpu-rasterization but neither fixed the problem.

We have also attached the chrome://gpu output (chrome_gpu_no_flags.docx).

Another curious detail is that the problem does not occur on our Mac machines, same Qt version.