Stuck on a code while creating a discord bot using python

this is the first time i am using this site. So, please do point out the mistake I did while writing this question. Thank you!

Actually I am making a discord bot using python. I was planning to use it as a bot which welcomes new user or notify when someone leave and stuff. So when I was writing the code about when the user joins my server the bot will send a embed message to the welcome channel, the embed message show’s some messages and a image. The code is mentioned below.

@bot.event
async def on_member_join(member):
    print('|---------------------------------------------------------->')
    print(f' New member joined as User: {member.name}, ID: ({member.id})')
    print('|---------------------------------------------------------->')

    welcome_channel_id = 1190887440433557544
    welcome_channel = member.guild.get_channel(welcome_channel_id)

    if not welcome_channel:
        print('|-------------------------->')
        print(' Welcome channel not found.')
        print('|-------------------------->')
        return
    
    images_folder = r'Z:Spooks [Discord Bot]Images'
    image_files = [f for f in os.listdir(images_folder) if f.lower().endswith(('.png', '.jpg', '.jpeg', '.gif', '.bmp', '.webp'))]

    if not image_files:
        print('|-------------------------------------->')
        print(' No valid image is found in the folder.')
        print('|-------------------------------------->')
        return

    random_image_file = random.choice(image_files)
    image_url = f'attachment://{random_image_file}'

    if welcome_channel:
        
        embed = discord.Embed(
            title=f'Welcome to the server, {member.name}!',
            description='We are glad to have you here. nWe hope you will find this server enjoyable.',
            color=0x3498db
        )

        embed.add_field(name = 'Rules', value = 'Strictly follow the rules mentioned in the Rules channel.', inline = False)
        embed.add_field(name = 'What to do next', value =  'Example 1, nExample 2, nExample 3', inline = False)

        embed.set_thumbnail(url = member.user.avatar_url)

        embed.set_image(url = image_url)

        await welcome_channel.send(embed=embed, file=discord.File(os.path.join(images_folder, random_image_file), filename=random_image_file))

In this code I tried to fetch some random images from a folder which contains images of dimension 320×320 (which is working fine). Then i want the user profile photo shows on top of the image, I tried bunch of different codes which is not working and then i thought i will add the user profile photo as thumbnail so I tried adding this

embed.set_thumbnail(url = member.user.avatar_url)

also I tried this too

embed.set_thumbnail(url = member.avatar_url)

But nothing seems to work, it always gives error similar to this (for the thumbnail part)

AttributeError: 'Member' object has no attribute 'user'. Did you mean: '_user'?

So, I appreciate the help on this topic. Either it give’s user profile photo on top of the image or as a thumbnail, both will work for me. And also I tried googling the image dimension required for embed message it says 320×320 which shows as a square image in the embed (I edited all my images to this dimension). Is it possible to show these image’s in rectangle.

Thanks in advance.