The authentication pop-up gets in loop when the first payment condition has requiresAuthentication: true. Continuing the purchase will only be possible if the page is reloaded.

• Configure a payment condition with requiresAuthentication: true;
• Make sure the payment condition is the first one;
• Use an existing email in the checkout to be identified;
• Go to the Payment step and the authentication pop-up;
• Log in using one of the options and notice that the pop-up is not closed.

• Change the order of the payment condition guaranteeing that the first option is not the one with requiresAuthentication: true;
• Set the parameter "defaultPaymentSystemToApplyOnUserOrderForm" in the orderForm Configuration via API for one without authentication, such as a credit card.