QPainter::drawText(QRectF, QString) has inconsistent behavior when QRectF is null

painter->drawText(QRectF(), "foo")

from PySide6 import QtWidgets, QtGui, QtCore, QtSvg
from PySide6.QtCore import Qt

app = QtWidgets.QApplication([])
widget = QtWidgets.QWidget()
layout = QtWidgets.QHBoxLayout(widget)
widget.setLayout(layout)
for test in ['invalid_SVG', 'valid_SVG', 'invalid_PXM', 'valid_PXM']:
    if 'invalid' in test:
        rect = QtCore.QRectF()  # invalid rect
    else:
        rect = QtCore.QRectF(25, 25, 75, 75)  # valid rect
    pixmap = QtGui.QPixmap(100, 100)
    painter = QtGui.QPainter()
    if 'SVG' in test:
        svg_gen = QtSvg.QSvgGenerator()
        buffer = QtCore.QBuffer()
        svg_gen.setOutputDevice(buffer)
        svg_gen.setSize(QtCore.QSize(100, 100))
        painter.begin(svg_gen)
    else:
        painter.begin(pixmap)
    painter.fillRect(QtCore.QRect(0, 0, 100, 100), Qt.white)
    painter.setPen(Qt.black)
    painter.drawText(rect, test)
    painter.end()
    if 'SVG' in test:
        pixmap.loadFromData(buffer.data(), "SVG")
    label = QtWidgets.QLabel(widget)
    layout.addWidget(label)
    label.setPixmap(pixmap)
widget.show()
app.exec()