Hi there,
I’m not able to recreate this on a sandbox site with just WooCommerce, PayPal Checkout, and Storefront Theme active.
I had a look at your site, and it seems like there is a slew of JavaScript errors coming from your theme Helik.

To check if these errors are causing PayPal to fail, temporarily swap out your theme to a standard one like Storefront Theme. If it works with Storefront, then you’ll need to reach out to your theme’s developers to hear about resolving those JavaScript issues.
Give that a try, and let us know what you find.
We haven’t heard back from you in a while, so I’m going to mark this as resolved – if you have any further questions, you can start a new thread.
Hi @etiennep thank you for reply. We had issue in strorefront theme as well.. But we found that the error occur only when we use currency conversion. So we removed the currency conversion and decided to go with only one currency. That solved our issue