Item2D dimensions are different when drawing the textured quad

Running the RenderModeMultiple Lancelot test case with and without RHI leads to stretched text.

This is when using the "Item2D" feature, i.e. when parenting a Quick (2D) subtree to a 3D object. RenderDoc reveals that the layerDimensions uniform (and the mvp matrix) is not as expected: (52, 30) instead of (87, 30). The correct one is (87, 30) because that is the size of the texture the Text item is rendered into. The (52, 30) value belongs to another Item2D....