How remove the border on the popup icon in QComboBox with style sheets?

[gabodev]

Hello !
I have this combobox and I need to not see that border:

I have tried with:

QComboBox QAbstractItemView::icon {
    border: 0px solid gray;
}

But it does not works.
Thank you in advance.

[J.Hilk]

Hi,

If I'm not mistaken, than

QComboBox QAbstractItemView{}

accesses the popup

what you're looking for should be

QComboBox::down-arrow{}

[gabodev]

@J.Hilk Hi! I have to change the question, I mean the icon on the popup. I want to remove the border that is marked in red.