PayPal Express button on product page adds product to cart and popup disappears?

Magento 2.4

I setup the express button to appear on the product page, which it does. Clicking it, opens the PayPal popup for a second or two, but the product is also added to the cart and the shop redirects to the product page and displays “Your product was added to te cart”.

So the popup is opened but never fully loads, because of the redirect to the product. Any idea what the cause might be?

Thanks!