CustomTkinter Label showing wrong time

Question

I wrote an application with the libraries Tkinter and CustomTkinter to make a world clock app.

When you first open the file, you'll see multiple buttons that, when clicked, show the times of the respective place.

Here is an image of the menu.

Now the problem is that all of these buttons end up showing the time for "Los Angeles, USA". It used to work fine, but since I made some refactoring changes, it's been like this.

import tkinter as tk
import customtkinter as ctk
from datetime import datetime
import pytz

# ------------ Preparation ------------
# Create the window
root = ctk.CTk()
root.iconbitmap("img\\icon.ico")  # custom defined icon
root.title("World Clock")
root.geometry("600x400")
root.configure(bg=("#ebf0f5", "#19191a"))
ctk.set_default_color_theme("theme.json")
ctk.set_appearance_mode("dark")

# Lists to better assort values
locations = ["Berlin, Germany", "Chennai, India", "London, UK", "New York, USA", "Tokyo, Japan", "Los Angeles, USA"]
timezones = ['Europe/Berlin', 'Asia/Kolkata', 'Europe/London', 'America/New_York', 'Asia/Tokyo', 'America/Los_Angeles']

# Import the photos necessary for the buttons / switch
images = [tk.PhotoImage(file='img\\germany.png'), tk.PhotoImage(file='img\\india.png'), 
            tk.PhotoImage(file='img\\uk.png'), tk.PhotoImage(file='img\\usa.png'), 
            tk.PhotoImage(file='img\\japan.png'), tk.PhotoImage(file='img\\usa.png')]

img = tk.PhotoImage(file='img\\theme.png')
switch_var = ctk.StringVar(value="on")
# -----------------------------------------------------


def menu():
    # Make the title
    title = ctk.CTkLabel(root, text="World Clock", text_font=("Audiowide", 25), padx=10, pady=7.5, 
                            borderwidth=1.5, text_color=('#008080','#017878'))
    title.place(relx=0.5, rely=0.125, anchor='center')

    # Switch for light/dark mode
    icon = ctk.CTkLabel(root, image=img)
    icon.place(relx=0.84, rely=0.082)
    theme_switch = ctk.CTkSwitch(root, height=25, width=45, command=set_mode, text=None, 
                                    variable=switch_var, onvalue="on", offvalue="off")
    theme_switch.place(relx= 0.84, rely= 0.095)
    
    # Make the buttons
    for i in range(6):
        button = ctk.CTkButton(root, image=images[i], text=locations[i], text_color=('#277575', '#369191'), 
                                command=lambda: display_time(i))
        buttons.append(button)
    
    # Place all the buttons
    buttons[0].place(relx=0.23, rely=0.35, anchor='center') # Berlin, Germany
    buttons[1].place(relx=0.77, rely=0.35, anchor='center') # Chennai, India
    buttons[2].place(relx=0.23, rely=0.6, anchor='center') # London, UK
    buttons[3].place(relx=0.77, rely=0.6, anchor='center') # New York, USA
    buttons[4].place(relx=0.23, rely=0.85, anchor='center') # Tokyo, Japan
    buttons[5].place(relx=0.77, rely=0.85, anchor='center') # Los Angeles, USA

def set_mode():
    # switch between light/dark mode
    if switch_var.get() == 'on':
        ctk.set_appearance_mode("dark")
    else:
        ctk.set_appearance_mode("light")

def clear_frame():
    for widget in root.winfo_children():
        widget.destroy()

def display_time(num):
    clear_frame()
    root.geometry("400x200")  # change window size for appropriate fit
    location = locations[num]  # set location
    display_time.tz = pytz.timezone(timezones[num])  # set timezone

    # Prepare the labels
    text = ctk.CTkLabel(root, text=location, text_font=("Arial", 16), padx=10, pady=7.5, 
                    borderwidth=3)
    text.place(relx=0.5, y=20, anchor='center')

    display_time.time_label = ctk.CTkLabel(root, text_font=("Arial", 42))
    display_time.time_label.place(relx=0.5, rely=0.5, anchor='center')
    display_time.date_label = ctk.CTkLabel(root, text_font=("Arial", 12))
    display_time.date_label.place(relx=0.5, y=175, anchor='center')

    update()

def update():
    time = datetime.now(display_time.tz).strftime("%H:%M:%S")
    date = datetime.now(display_time.tz).strftime(f"%A, %d.%m.%Y") 

    display_time.time_label.configure(text=time)
    display_time.date_label.configure(text=date)
    root.after(1000, update)  # update every second

# ---------- Run ----------
buttons = []
menu()

root.mainloop()

Where did I make a mistake?

As I am a beginner in programming, I would also request for some feedback on my code structure.

I thank you in advance.