Quantity doubles on cart page

Hi team,

We’re seeing cart quantities double on our store, and we’ve traced it to cart items left behind with a _wc_stripe_calculation suffix on their cart item key.

Environment

• Payment Plugins for Stripe WooCommerce 4.0.16
• WooCommerce 11.1.2
• Flatsome 3.20.5
• Apple Pay and Google Pay enabled

Steps to reproduce

1. Open any product page (simple or variable) and set quantity to 3.
2. Click “Add to cart”. The cart correctly contains 3.
3. Click “View cart”.
4. The cart now shows two lines for the same product, 3 each (6 total), and the subtotal reflects 6.

It doesn’t happen every time, but it’s easy to reproduce.

What we found

The cart item keys on the cart page show the duplicate is a leftover from the plugin’s calculation process:

cart[f0e2c54e09e81ac2fde8ec4c1891264f][qty]                         -> 3  (the real add)
cart[f0e2c54e09e81ac2fde8ec4c1891264f_wc_stripe_calculation][qty]   -> 3  (the duplicate)

Other items already in the cart also ended up re-keyed with the _wc_stripe_calculation suffix, but those weren’t duplicated.

When the duplication happened, we could see a ?wc-ajax=wc_stripe_frontend_request&path=/wc-stripe/v1/cart/calculation request. It looks like the temporary calculation cart isn’t being fully cleaned up or restored, and the suffixed items persist in the customer’s real session cart.

Disabling the Mini-cart location for Apple Pay and Google Pay did not fix it. We suspect the cart-page express buttons trigger the same calculation request.

Temporary workaround

We’re currently running this snippet, which removes the leaked items (or re-keys them if the original is missing) when the cart loads from the session. It has resolved the issue for us:

php

add_action( 'woocommerce_cart_loaded_from_session', 'fix_stripe_calculation_cart_items', 99 );
function fix_stripe_calculation_cart_items( $cart ) {
	if ( isset( $_GET['wc-ajax'] ) && 'wc_stripe_frontend_request' === $_GET['wc-ajax'] ) {
		return;
	}
	$suffix   = '_wc_stripe_calculation';
	$len      = strlen( $suffix );
	$contents = $cart->get_cart_contents();
	$changed  = false;
	foreach ( $contents as $key => $item ) {
		if ( substr( $key, -$len ) !== $suffix ) {
			continue;
		}
		$original_key = substr( $key, 0, -$len );
		if ( isset( $contents[ $original_key ] ) ) {
			unset( $contents[ $key ] );
		} else {
			$item['key']               = $original_key;
			$contents[ $original_key ] = $item;
			unset( $contents[ $key ] );
		}
		$changed = true;
	}
	if ( $changed ) {
		$cart->set_cart_contents( $contents );
		$cart->calculate_totals();
	}
}

Could you look into why the _wc_stripe_calculation items persist in the session after the calculation request? I’m happy to provide more details or test a patch.

Thanks