REG->6.5: Memory/Reference Leak with connecting signals to lambda functions referencing "self"

from PySide6 import QtCore, QtWidgets
import psutil

class Leaker:
    def __init__(self):
        parent = None
        parent = QtWidgets.QWidget()    # this line seemingly makes PySide < 6.5.0 not leak
        wgt= QtWidgets.QSpinBox(parent)
        wgt.valueChanged.connect(self.mkChangeCallback(wgt))

    def mkChangeCallback(self, w):
        return lambda *args: self.widgetChanged(w, *args)
        
    def widgetChanged(self, w, *args):
        pass

app = QtWidgets.QApplication([])
timer = QtCore.QTimer()
proc = psutil.Process()

rss0 = proc.memory_info().rss

cnt = 0
def timer_cb():
    global cnt
    rss = proc.memory_info().rss
    print(f'{cnt}: {(rss - rss0)/1048576:.1f} MB')
    Leaker()
    cnt += 1
    if cnt > 500:
        timer.stop()
        app.exit()

timer.timeout.connect(timer_cb)
timer.start(0)
app.exec() if hasattr(app, 'exec') else app.exec_()