Playing around with Yubiko OTP on python, and all inputs coming back as invalid from valid yubikey

Question

I'm a hobbyist coder and am trying to learn Passkey authentication. I got an API key from Yubico, and was trying to test it using python and flask. For some reason though, everytime I click the Yubikey and have the code entered in an input box, it always comes out as invalid. I double checked on the demo.yubikey.com and all the text generated by the yubikey is valid, so I'm stuck.

Here is my code:

from flask import Flask, request, render_template
from yubico_client.yubico import Yubico
from dotenv import load_dotenv
import os

load_dotenv()

app = Flask(__name__)

def validate_passkey(passkey):
    client_id = os.getenv('YUBICO_CLIENT_ID')
    secret_key = os.getenv('YUBICO_SECRET_KEY')
    client = Yubico(client_id, secret_key)
    try:
        return client.verify(passkey)
    except Exception:
        return False

@app.route('/', methods=['GET', 'POST'])
def login():
    error = None
    if request.method == 'POST':
        passkey = request.form.get('passkey')
        if validate_passkey(passkey):
            return 'Logged in!'
        else:
            error = '❌ Invalid passkey'
    return render_template('secure login login.html', error=error)

if __name__ == '__main__':
    app.run(debug=True)

and i have a very simple HTML form to take they input from the Yubikey:

    <form method="POST">
    <input type="text" name="passkey" placeholder="Enter your YubiKey passkey">
    <input type="submit" value="Login">
</form>

{% if error %}
    <p class="error">{{ error }}</p>
{% endif %}