woocommerce order-pay page redirect back to checkout

Question

I have a problem with woocommerce checkout page. when user field all items in the checkout form and submit form to go for payment it redirects to current page.

also when I check in network xhr requests I see that it successfully done

{"result":"success","redirect":"https:\/\/tajhizman.ir\/checkout\/order-pay\/11395\/?key=wc_order_LsPv0uxqfXJOW","order_id":11395}

I have copied url passed in 'redirect' and opened in new tab its go back to checkout page.

https://tajhizman.ir/checkout/order-pay/11395/?key=wc_order_LsPv0uxqfXJOW goes back to https://tajhizman.ir/checkout/ page.

is there any way to fix it?