QColordialog - cannot input/paste values without # (pound) symbol

The input field for the HEX color in the Qcolordialog only accepts values when the # (pound) symbol is typed first. This means that if I copy and paste a Hex value from another application that does not list this symbol, the input is invalid and not pasted.

Expected result

I would expect to be able to start typing any value (6 characters) and that Qt would also accept the Hex code. Applications like Photoshop or Affinity Designer don't require the # symbol at all. And when it is used, the value is also accepted.

This was originally posted as a bug for FreeCAD, the developers looked into it and concluded the bug is an upstream Qt bug. Link to the original report:

https://github.com/FreeCAD/FreeCAD/issues/8317