QT quick 3d physics- Cannon example- shadow flickering

How to reproduce:

1. Open the Qt quick 3d physics -cannon example
2. Press on fire
3. You can see on the left side that the shadow will start to flicker after that the boxes have been hit

Expected result:

The shadow should not be moving

Actual result:

The shadow is flickering

Special notes:

After testing it seems that simply firing the canon causes the flickering to start. The ball does not need to touch any of the red cubes, simply to be fired for the flickering to occur.