Create lambda functions in a loop for PyQt5 Signals?

Question

I'm trying to connect a function to buttons created inside a loop, with a different argument for the function for each button. This is my attempt:

from PyQt5 import QtWidgets, QtGui, QtCore

class GUI(QtWidgets.QWidget):

    def __init__(self):
        super().__init__()
        layout = QtWidgets.QVBoxLayout()
        self.setLayout(layout)
        self.show()
        for num in range(5):
            b = QtWidgets.QPushButton(str(num))
            string = f"You clicked button {num}!"
            b.clicked.connect(lambda x=string: self.func(x))
            layout.addWidget(b)

    def func(self, thing):
        print(thing)


app = QtWidgets.QApplication([])
win = GUI()
app.exec_()

This creates a GUI with 5 buttons, but clicking them just prints "False" to the console.

Initially I had connect(lambda: self.func(string)) which caused each button to print You clicked button 4! because of this: https://docs.python.org/3/faq/programming.html#why-do-lambdas-defined-in-a-loop-with-different-values-all-return-the-same-result

But I have no idea why it's now passing False. I tried using the same functions and logic outside of PyQt as below and that successfully printed 0 1 2 3 4 to the console.

func_list = []
for num in range(5):
    func_list.append(lambda x=num: func(x))

def func(thing):
    print(thing)

for f in func_list:
    f()