Checkout Error: Tokenization Script Not Loaded with UPE on Classic Theme

[mustafauysal]

Describe the bug

When New Checkout Experience (UPE) is enabled on a classic theme, the "Use a New Payment Method" radio button is displayed but does not function correctly upon submitting the checkout form. After investigating, I found that the ...woocommerce/assets/js/frontend/tokenization-form.min.js is not added to the page. This script is called in the payment_fields method from woocommerce-gateway-stripe/includes/payment-methods/class-wc-stripe-upe-payment-gateway.php.

As a workaround, loading tokenization_script within payment_scripts resolves the issue. It's unclear if this is a known issue or if it conflicts with other plugins, but it might be worth investigating.

To Reproduce
Steps to reproduce the behavior:

1. Enable UPE on a classic theme.
2. Go to the checkout page.
3. See the "Use a New Payment Method" radio button - unselected
4. Attempt to submit the form.
5. Observe that the payment form does not function as expected.

Expected behavior
tokenization-form.min.js should be loaded on the checkout page and it removes when Use a New Payment Method is the only option

Environment (please complete the following information):

• WordPress Version: 6.6.2
• WooCommerce Version: 9.3.3
• Stripe Plugin Version: 8.8.1
• Browser [e.g. chrome, safari] and Version: Version 1.71.118 Chromium: 130.0.6723.70 (not related with browser, tho)
• Any other plugins installed:

Aelia Foundation Classes for WooCommerce: by Aelia – 2.6.0.241007
Advanced Custom Fields PRO: by WP Engine – 6.3.9
Advanced Custom Fields: Table Field: by Johann Heyne – 1.3.26
AffiliateWP: by AffiliateWP – 2.27.2
Antispam Bee: by pluginkollektiv – 2.11.6
ATUM Multi-Inventory: by Stock Management Labs™ – 1.9.2
ATUM Inventory Management for WooCommerce: by Stock Management Labs™ – 1.9.41.2
Login by Auth0: by Auth0 – 4.6.2
Auto Image Attributes From Filename With Bulk Updater: by Arun Basil Lal – 4.4
WP Contact Form HubSpot: by CRM Perks – 1.3.4
Classic Widgets: by WordPress Contributors – 0.3
Contact Form 7: by Takayuki Miyoshi – 5.9.8
GTM4WP - A Google Tag Manager (GTM) plugin for WordPress: by Thomas Geiger – 1.20.2
Easy Table of Contents: by Magazine3 – 2.0.70
File Upload Types by WPForms: by WPForms – 1.5.0
UPS Live Rates and Access Points: by Octolize – 3.0.0
Folders Pro: by Premio – 3.0.6
Head, Footer and Post Injections: by Stefano Lissa – 3.2.8
Jetpack Boost: by Automattic - Jetpack Site Speed team – 3.5.2
JSON API Auth: by Ali Qureshi – 2.9.1
JSON API: by Dan Phiffer – 1.1.1
Kirki Customizer Framework: by Themeum – 5.1.0
HubSpot All-In-One Marketing - Forms, Popups, Live Chat: by HubSpot – 11.1.66
LiteSpeed Cache: by LiteSpeed Technologies – 6.5.2
MWB HubSpot for WooCommerce: by MakeWebBetter – 1.5.8
Order Export for WooCommerce: by JEM Plugins – 3.24
Post Duplicator: by Metaphor Creations – 2.36
Post Types Order: by Nsp Code – 2.3.2
Redirection: by John Godley – 5.5.0
Regenerate Thumbnails: by Alex Mills (Viper007Bond) – 3.1.6
Rank Math SEO: by Rank Math – 1.0.230
Stream: by XWP – 4.0.2
Ultimate Blocks: by Ultimate Blocks – 3.2.2
UpdraftPlus - Backup/Restore: by TeamUpdraft
DavidAnderson – 2.24.6.26
User Role Editor: by Vladimir Garagulya – 4.64.2
Advanced Shipment Tracking for WooCommerce: by zorem – 3.6.9
Checkout Field Editor for WooCommerce: by ThemeHigh – 2.0.4
Advanced Order Export For WooCommerce: by AlgolPlus – 3.5.5
Payment Plugins Braintree For WooCommerce: by Payment Plugins
Product Feed PRO for WooCommerce: by AdTribes.io – 13.3.8.1
Integration for WooCommerce and QuickBooks Pro: by CRM Perks – 1.2.6
Aelia Currency Switcher for WooCommerce: by Aelia – 5.2.0.241007
WooCommerce PayPal Standard (Multi Account): by Aelia – 1.3.3.180413
Cart Insights for WooCommerce: by Berend de Jong – 1.4.4
WooCommerce Currency Switcher - AffiliateWP Integration: by Aelia – 1.3.15.240910
WooCommerce EU VAT Assistant: by Aelia – 2.1.17.241007
EU/UK VAT Compliance for WooCommerce (Free): by David Anderson – 1.31.1
WooCommerce Stripe Gateway: by Stripe – 8.8.1
WooCommerce Legacy REST API: by WooCommerce – 1.0.4
WooCommerce PayPal Payments: by WooCommerce – 2.9.3
Woocommerce Side Cart Premium: by XootiX – 3.1
WooCommerce: by Automattic – 9.3.3
Wordfence Security: by Wordfence – 7.11.7
Bootstrap Blocks: by Liip AG – 5.2.0
WP Crontrol: by John Blackbourn – 1.17.0
WP Migrate: by WP Engine – 2.7.0
Custom Product Tabs for WooCommerce: by Code Parrots – 1.8.5
YITH WooCommerce Badge Management: by YITH – 3.11.0