It seems that using software rendering breaks the Blend effect from Qt5Compat.GraphicalEffects

Setting the environment variable `QT_QUICK_BACKEND=software` seems to break the `Blend {}` type from `import Qt5Compat.GraphicalEffects`

When I enable software rendering the pixels don't get blended and only the texture image gets displayed.

I'm using the Blend effect like this:
```
    Blend

{         anchors.fill: parent         source: grainTexture         foregroundSource: background         mode: "screen"     }

```

Normal with Direct3D rendering:

With software rendering enabled: