[BUG]: PaymentElement doesn't display correct locale in Custom Checkout

[jstcki]

What happened?

With a checkout session like

const session = await stripe.checkout.sessions.create({
    mode: "subscription",
    ui_mode: "custom",
    locale: "de",
    // ...
});

The Payment Element (rendered within a react-stripe-js <CustomCheckoutProvider>) still displays English labels.

(With Embedded Checkout it works fine)

Environment

Any browser, custom_checkout_beta_3

Reproduction

No response