in Attached example pathToRect returns different rects. Only one rect is valid even though both path are equal and are only created in a different way.

When you run you will get this output:

First path is rect true | bouding rect QRectF(47,0 27x88) | RESULT QRectF(74,88 -27x-88)
Second path is rect true | bouding rect QRectF(47,0 27x88) | RESULT QRectF(47,0 27x88)

This only works if shape points are given in a defined order.