QDockWidgets border distortion in Fedora Gnome

Project Discussion
1

Hi!
Please tell me how to solve this problem: when using QDockWidget in Fedora Gnome with version Qt5.15, the custom qss style sheet is not applied for the border of the pinned QDockWidget, as well as for the border of the QFrame placed in QDockWidget. Instead, the system decorator for the QDockWidget border is displayed, which cannot be disabled using the style sheet. Is there a way to disable the system decorator?

Distorted borders (Fedora Gnome, Qt5.15)

Screenshot from 2021-06-21 09-48-39

Here is the stylesheet I am applying:

QMainWindow {
    background: #2C2C34;
}
QMainWindow::separator {
    width: 1px;
    height: 1px;
    background: #2C2C34;
}

QFrame {
    border-left: 1px solid #32363F;
    border-bottom: 1px solid #32363F;
    border-right: 1px solid #32363F;
    border-top: none;
    background-color: #292930;
}

QDockWidget {
    font-size: 8pt;
    color: #A0A5AA;
}
QDockWidget::title {
    padding-left: 12px;
    padding-top: 3px;
    padding-bottom: 3px;
    text-align: center left;
    border-left: 1px solid #32363F;
    border-top: 1px solid #32363F;
    border-right: 1px solid #32363F;
    background: #25272C;
}
QDockWidget::close-button,
QDockWidget::float-button {
    icon-size: 20px;
    padding-top: 0px;
    padding-bottom: 0px;
    border: none;
    background: #25272C;
}
QDockWidget::close-button:hover,
QDockWidget::float-button:hover {
    background: rgb(52, 59, 72);
}
QDockWidget::close-button:pressed,
QDockWidget::float-button:pressed {
    background-color: rgb(85, 170, 255);
}
QDockWidget::close-button {
    min-width: 20px;
    min-height: 20px;
    width: 20px;
    height: 20px;
    top: 1px; bottom: 0px; right: 1px;
    subcontrol-position: center right;
    subcontrol-origin: margin;
    position: absolute;

}
QDockWidget::float-button {
    min-width: 20px;
    min-height: 20px;
    width: 20px;
    height: 20px;
    top: 1px; bottom: 0px; right: 24px;
    subcontrol-position: center right;
    subcontrol-origin: margin;
    position: absolute;

}
2

Solving the problem:

app.setStyle(QStyleFactory::create("Fusion"));