WASM: Running OpenGL ES2 exampels results in black screen

Steps to reproduce:

1. Run example with OpenGL ES2 on WASM,e.g.:
   1. https://doc.qt.io/qt-6/qtopengl-openglwindow-example.html
   2. https://doc.qt.io/qt-6/qtopengl-cube-example.html

Expected: Examples are visible.

Actual: Black screen - no content visible. 

Reproducibility: 100%