painter.drawline() , overlapping opacity problems with 100% opaque pen.

from PySide2 import QtGui, QtCore, QtWidgets

class TestView(QtWidgets.QGraphicsView):

    def __init__(self, parent=None):
        super(TestView, self).__init__(parent)

        self.setOptimizationFlag(QtWidgets.QGraphicsView.DontAdjustForAntialiasing)
        self.setRenderHint(QtGui.QPainter.Antialiasing, False)
        self.setRenderHint(QtGui.QPainter.HighQualityAntialiasing, False)
        self.setRenderHint(QtGui.QPainter.NonCosmeticDefaultPen, False)
        self.setViewportUpdateMode(QtWidgets.QGraphicsView.FullViewportUpdate)
        self.setTransformationAnchor(QtWidgets.QGraphicsView.AnchorUnderMouse)
        self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

    def wheelEvent(self, event):
        self.setTransformationAnchor(QtWidgets.QGraphicsView.AnchorUnderMouse)

        inFactor = 1.15
        outFactor = 1 / inFactor

        if event.delta() > 0:
            zoomFactor = inFactor
        else:
            zoomFactor = outFactor

        self.scale(zoomFactor, zoomFactor)

class TestItem(QtWidgets.QGraphicsItem):

    def __init__(self):
        super(TestItem, self).__init__()

    def boundingRect(self):
        return QtCore.QRect(0, 0, 200, 400)

    def shape(self):
        path = QtGui.QPainterPath()
        path.addRect(self.boundingRect())
        return path

    def paint(self, painter, option, widget):
        brush = QtGui.QBrush(QtGui.QColor(70, 70, 70, 255))
        painter.setBrush(brush)

        painter.drawRoundedRect(0, 0, 200, 400, 20, 20)

        pen = QtGui.QPen(QtGui.QColor(200, 200, 200, 255))
        pen.setWidth(1)
        painter.setPen(pen)

        painter.drawLine(50, 50, 50, 300)
        painter.drawLine(50, 80, 50, 200)
        painter.drawLine(50, 80, 150, 80)


view = TestView()
scene = QtWidgets.QGraphicsScene()
view.setScene(scene)

item = TestItem()
scene.addItem(item)
    
view.show()